JP3841288B2 - Photosensitive polyimide resin precursor composition, optical polyimide and optical waveguide obtained therefrom - Google Patents

Description

【００２３】
（式中、Ａｒは１，４−ジヒドロピリジン環への結合位置に対してオルソ位にニトロ基を有する芳香族基を示し、Ｒ₁ は水素原子又は炭素原子数１〜３のアルキル基を示し、Ｒ₂、Ｒ₃、Ｒ₄ 及びＲ₅ はそれぞれ独立に水素原子又は炭素原子数１又は２のアルキル基を示す。）
で表される１，４−ジヒドロピリジン誘導体０．０１重量部以上、５重量部未満と、
（ｃ）ポリエチレングリコール、ポリエチレングリコールモノメチルエーテル、ポリエチレングリコールジメチルエーテル、ポリエチレングリコールモノフェニルエーテル、ポリエチレングリコールジフェニルエーテル、ポリプロピレングリコール、ポリプロピレングリコールモノメチルエーテル、ポリプロピレングリコールジメチルエーテル、ポリプロピレングリコールモノフェニルエーテル及びポリプロピレングリコールジフェニルエーテルから選ばれる少なくとも１種のグリコール（エーテル）５〜５０重量部とを含有することを特徴とする感光性ポリイミド樹脂前駆体組成物が提供される。
【００２４】
また、本発明によれば、上記感光性ポリイミド樹脂前駆体組成物に紫外線を照射した後、露光後加熱し、現像し、加熱して得られる光学用ポリイミド樹脂が提供される。更に、本発明によれば、上記光学用ポリイミド樹脂からなるコア層をクラッド層で包含してなる光導波路が提供される。
【００２５】
以上のほか、本発明によれば、前記ポリアミド酸と、このポリアミド酸１００重量部に対して、前記１，４−ジヒドロピリジン誘導体０．０１重量部以上、５重量部未満と、重量平均分子量２００〜２０００の前記グリコール（エーテル）２０〜４０重量部とを含有する感光性ポリイミド樹脂前駆体組成物を基板上に塗布し、感光性樹脂膜を形成し、マスクを介して紫外線を照射した後、露光後加熱し、現像し、加熱して、断面が方形のコア層を形成することを特徴とする光導波路の製造方法が提供される。
【００２６】
【発明の実施の形態】
本発明による感光性ポリイミド樹脂前駆体組成物は、テトラカルボン酸二無水物とジアミンとから得られるポリアミド酸と感光剤と共に、ポリエチレングリコール、ポリエチレングリコールモノメチルエーテル、ポリエチレングリコールジメチルエーテル、ポリエチレングリコールモノフェニルエーテル、ポリエチレングリコールジフェニルエーテル、ポリプロピレングリコール、ポリプロピレングリコールモノメチルエーテル、ポリプロピレングリコールジメチルエーテル、ポリプロピレングリコールモノフェニルエーテル及びポリプロピレングリコールジフェニルエーテルから選ばれる少なくとも１種のグリコール（エーテル）を溶解調整剤として含んでなるものである。
【００２７】
本発明において、上記テトラカルボン酸二無水物としては、特に、限定されるものではないが、例えば、ピロメリット酸二無水物、３，３’，４，４’−ビフェニルテトラカルボン酸二無水物、２，２−ビス（２，３−ジカルボキシフェニル）プロパン二無水物、２，２−ビス（３，４−ジカルボキシフェニル）プロパン二無水物、３，３’，４，４’−ベンゾフェノンテトラカルボン酸二無水物、ビス（３，４−ジカルボキシフェニル）エーテル二無水物、ビス（３，４−ジカルボキシフェニル）スルホン酸二無水物等を挙げることができる。
【００２８】
しかし、本発明によれば、上記テトラカルボン酸二無水物としては、特に、分子内にフッ素原子を含有するもの（以下、フッ素置換テトラカルボン酸二無水物という。）が好ましい。このようなフッ素置換テトラカルボン酸二無水物としては、例えば、２，２−ビス（３，４−ジカルボキシフェニル）へキサフルオロプロパン二無水物、４，４−ビス（３，４−ジカルボキシトリフルオロフェノキシ）テトラフルオロベンゼン二無水物、１，４−ビス（３，４−ジカルボキシトリフルオロフェノキシ）テトラフルオロベンゼン二無水物、（トリフルオロメチル）ビロメリット酸二無水物、ジ（トリフルオロメチル）ピロメリット酸二無水物、ジ（ヘプタフルオロプロピル）ピロメリット酸二無水物等を挙げることができる。
【００２９】
他方、上記ジアミンとしては、例えば、ｍ−フェニレンジアミン、ｐ−フェニレンジアミン、３，４’−ジアミノジフェニルエーテル、４，４’−ジアミノジフェニルエーテル、４，４’−ジアミノジフェニルスルホン、３，３’−ジアミノジフェニルスルホン、２，２−ビス（４−アミノフェノキシフェニル）プロパン、１，３−ビス（４−アミノフェノキシ）ベンゼン、１，４−ビス（４−アミノフェノキシ）ベンゼン、２，４−ジアミノトルエン、２，６−ジアミノトルエン、４，４’−ジアミノジフェニルメタン、４，４’−ジアミノ−２，２’−ジメチルビフェニル等を挙げることができる。
【００３０】
しかし、テトラカルボン酸二無水物におけると同様に、本発明によれば、上記ジアミンとしては、特に、分子内にフッ素原子を含有するもの（以下、フッ素置換ジアミンという。）が好ましい。このようなフッ素置換ジアミンとしては、例えば、２，２’−ビス（トリフルオロメトキシ）−４，４’−ジアミノビフェニル（ＴＦＭＯＢ）、３，３’−ジアミノ−５，５’−ビス（トリフルオロメチル）ビフェニル、２，２−ビス（４−アミノフェニル）へキサフルオロプロパン（ＢＡＡＦ）、２，２−ビス〔４−（４−アミノフェノキシ）フェニル〕へキサフルオロプロパン（ＨＦＢＡＰＰ）、２，２’−ビス（トリフルオロメチル）−４，４’−ジアミノビフェニル（ＴＦＭＢ）、２，２−ビス（３−アミノ−４−ヒドロキシフェニル）へキサフルオロプロパン（ＢＩＳ−ＡＰ−ＡＦ）、２，２−ビス（３−アミノ−４−メチルフェニル）へキサフルオロプロパン（ＢＩＳ−ＡＴ−ＡＦ）、２，２’−ジフルオロベンジジン（ＦＢＺ）、４，４’−ビス（アミノオクタフルオロ）ビフェニル、３，５−ジアミノベンゾトリフルオライド、１，３−ジアミノ−２，４，５，６−テトラフルオロベンゼン等を挙げることができる。
【００３１】
本発明において、上記ポリアミド酸は、上述したようなテトラカルボン酸二無水物とジアミンとを常法に従って反応させることによって得ることができる。即ち、例えば、窒素雰囲気下、ジアミンを適宜の有機溶媒に溶解させた溶液とこのジアミンと等モル量のテトラカルボン酸二無水物を加え、室温にて、５〜２０時間程度、攪拌すれば、ポリアミド酸の溶液を粘性のある溶液として得ることができる。
【００３２】
上記溶媒としては、従来より、ポリアミド酸の製造に用いられるものであれば、特に限定されるものではないが、例えば、Ｎ，Ｎ−ジメチルアセトアミド（ＤＭＡｃ）やＮ−メチル−２−ピロリドン（ＮＭＰ）等の極性溶媒が好ましく用いられ、特に、熱分解せず、透明性にすぐれるという点から、ＤＭＡｃが好ましく用いられる。
【００３３】
本発明によれば、このようにして得られるポリアミド酸のなかでも、次の一般式（II）
【００３４】
【化７】

【００３５】
（式中、Ｒ₆ は次式（IIa)、(IIb)、(IIc)、(IId) 及び (IIe)
【００３６】
【化８】

【００３７】
で表される４価基から選ばれる少なくとも１つの４価基を示し、Ｒ₇ は次式（IIf)、(IIg)、(IIh) 及び (IIi)
【００３８】
【化９】

【００３９】
で表される２価基から選ばれる少なくとも１つの２価基を示す。）
で表される繰返し単位を有する
ポリアミド酸を用いて得られるポリイミド樹脂が低い屈折率を有し、また、光導波路におけるコア層とする場合に、クラッドとの比屈折率差を容易に調整することができるので好ましく用いられる。
【００４０】
本発明による感光性ポリイミド樹脂前駆体組成物は、このようなポリアミド酸１００重量部に対して、一般式（Ｉ）
【００４１】
【化１０】

【００４２】
（式中、Ａｒは１，４−ジヒドロピリジン環への結合位置に対してオルソ位にニトロ基を有する芳香族基を示し、Ｒ₁ は水素原子又は炭素原子数１〜３のアルキル基を示し、Ｒ₂、Ｒ₃、Ｒ₄ 及びＲ₅ はそれぞれ独立に水素原子又は炭素原子数１又は２のアルキル基を示す。）
で表される１，４−ジヒドロピリジン誘導体を感光剤として０．０１重量部以上、５重量部未満と、前記グリコール（エーテル）を溶解調整剤として５〜５０重量部の範囲で配合してなるものである。
【００４３】
上記感光剤の具体例として、例えば、１−エチル−３，５−ジメトキシカルボニル−４−（２−ニトロフェニル）−１，４−ジヒドロピリジン、１−メチル−３，５−ジメトキシカルボニル−４−（２−ニトロフェニル）−１，４−ジヒドロピリジン、１−プロピル−３，５−ジメトキシカルボニル−４−（２−ニトロフェニル）−１，４−ジヒドロピリジン、１−プロピル−３，５−ジエトキシカルボニル−４−（２−ニトロフェニル）−１，４−ジヒドロピリジン等を挙げることができる。
【００４４】
しかし、本発明によれば、上述した種々の感光剤のなかでも、特に、コストとＣ−Ｈ結合による光吸収が少ないという点から、１−エチル−３，５−ジメトキシカルボニル−４−（２−ニトロフェニル）−１，４−ジヒドロピリジン（以下、ＥＤＨＰという。）が好ましく用いられる。
【００４５】
このような１，４−ジヒドロピリジン誘導体は、例えば、置換ベンズアルデヒドとその２倍モル量のアルキルプロピオレート（プロパルギル酸アルキルエステル）と相当する第１級アミンとを氷酢酸中で還流下に反応させることによって得ることができる（Khim. Geterotsikl. Soed., pp. 1067-1071, 1982)。
【００４６】
このような感光剤は、前記ポリアミド酸１００重量部に対して、０．０１重量部以上、５重量部未満の範囲で用いられ、好ましくは、０．０５〜２重量部の範囲で用いられる。本発明によれば、前記ポリアミド酸１００重量部に対して、感光剤を５重量部以上用いて、感光性ポリイミド樹脂前駆体組成物とすれば、これより得られるポリイミド樹脂が近赤外領域において光吸収するようになる。しかし、感光剤の配合割合が前記ポリアミド酸１００重量部に対して、０．０１重量部未満では、得られる感光性ポリイミド樹脂前駆体組成物に紫外線照射し、現像して、パターン形成する際に、十分なコントラストを得ることができない。
【００４７】
更に、本発明による感光性ポリイミド樹脂前駆体組成物によれば、ポリアミド酸に対する感光剤の配合割合が少ないのみならず、得られる感光性ポリイミド樹脂前駆体組成物を露光させるための露光量自体も、従来から知られている感光性ポリイミド樹脂前駆体組成物に比べて低減することができる。即ち、従来の感光性ポリイミド樹脂前駆体組成物においては、適正な露光量が３００〜１０００ｍＪ／ｃｍ² であるのに対して、本発明による感光性ポリイミド樹脂前駆体組成物によれば、５〜２０ｍＪ／ｃｍ² の範囲の露光量によって、十分な解像が可能である。
【００４８】
このように、本発明によれば、前述したように、ポリアミド酸の構造中にフッ素原子を導入することによって、ポリアミド酸の透明性が向上し、その結果として、ポリアミド酸に対する感光剤の割合を低減し、更に、露光量をも低減しても、光に対して十分な感度を有し、露光後、現像に際して、高いコントラストを与える。
【００４９】
本発明によれば、ポリアミド酸に上記感光剤と共に、前記グリコール（エーテル）を溶解調整剤として配合して、感光性ポリイミド樹脂前駆体組成物を得る。このような溶解調整剤としてのグリコール（エーテル）は、重量平均分子量が、通常、１００〜３０００、好ましくは、２００〜２０００、最も好ましくは、３００〜１０００の範囲にある。本発明によれば、上記溶解調整剤は、ポリアミド酸を加熱し、硬化（イミド化）させる際に、残存溶剤と共に樹脂外に揮散して、最終的に樹脂中に残存しないので、形成されるポリイミド樹脂の透明性等、光学用樹脂として要求される特性に有害な影響を与えない。
【００５０】
本発明によれば、このような溶解調整剤は、前記ポリアミド酸１００重量部に対して、５〜５０重量部、好ましくは、１０〜４０重量部の範囲で用いられる。溶解調整剤の割合が前記ポリアミド酸１００重量部に対して、５重量部よりも少ないときは、得られる感光性ポリイミド樹脂前駆体組成物からなる樹脂膜を露光させた後、現像する際に、樹脂膜の厚みの低減（即ち、膜減り）を抑制する効果に乏しく、現像後の残膜率は、通常、５０％以下であり、また、得られるパターンの断面も上に凸の台形形状である。他方、５０重量部を越えるときは、ポリアミド酸との相溶性が悪くなって、解像度が低下するおそれがある。
【００５１】
本発明によれば、溶解調整剤を用いることによって、得られる感光性ポリイミド樹脂前駆体組成物からなる樹脂膜に光照射して露光させた後、現像に際して、上記樹脂膜の露光部と未露光部の現像液に対する溶解性に著しい差を生じさせ、かくして、現像に際して、露光部を殆ど溶解させることなく、未露光部を溶解除去することができるので、上記樹脂膜の残膜率を向上させることができ、好ましい態様によれば、溶解調整剤の配合量を選択することによって、得られるパターンの形状を制御することができる。
【００５２】
即ち、本発明に従って、上記溶解調整剤を前記ポリアミド酸１００重量部に対して、２０〜４０重量部、好ましくは、２５〜３５重量部の範囲で用いることによって、８０％以上の残膜率を保持することができ、しかも、そのパターンの断面形状を方形とすることができる。これによって、従来、困難であった正方形の断面形状（アスペクト比１）や、更には、縦長の断面形状（アスペクト比１以上）を有するパターンをウェットエッチングによって形成することができる。
【００５３】
本発明によれば、このように、溶解調整剤を適正な配合量で用いることによって、得られる感光性ポリイミド樹脂前駆体組成物からなる樹脂膜に光照射して露光させた後、現像に際して、上記樹脂膜の露光部と未露光部の現像液に対する溶解性に大きな差を生じさせ、かくして、現像に際して、露光部を殆ど溶解させることなく、未露光部を溶解除去することができるので、得られるパターンの形状を制御することができる。
【００５４】
本発明によれば、このように、ポリアミド酸に感光剤と溶解調整剤を配合することによって、高感度の感光性を有する感光性ポリイミド樹脂前駆体組成物を得ることができ、しかも、このような感光性ポリイミド樹脂前駆体組成物によれば、大面積加工が可能である。即ち、従来の光素子におけるパターン形成は、前述したように、リアクティブイオンエッチング法をはじめとするドライプロセスによっているので、作業時間が長く、量産性に乏しいのに対して、本発明による感光性ポリイミド樹脂前駆体組成物を用いるパターン形成には、これらの欠点がなく、しかも、大幅に加工コストを低減することができる。
【００５５】
更に、本発明に従って、感光性ポリイミド樹脂前駆体組成物のウェットエッチングによって得られるパターンの表面は、側面を含めて、非常に滑らかであるので、従来、リアクティブイオンエッチング法をはじめとするドライブロセスで問題となっていたパターン側面の凹凸による光散乱がなく、透明性（光の透過率）に極めてすぐれる。
【００５６】
本発明による光学用ポリイミド樹脂は、このような感光性ポリイミド樹脂前駆体組成物から得ることができる。詳しくは、例えば、感光性ポリイミド樹脂前駆体組成物をシリコン基板、石英基板、金属箔、ガラス板、高分子フィルム等の基材の表面に塗布し、初期乾燥させて、上記感光性ポリイミド樹脂前駆体組成物からなる樹脂膜を形成させた後、所望のパターンが得られるように、ガラスマスク等を介し、上記樹脂膜に紫外線を照射する。次に、この樹脂膜における光反応を完結させるために、通常、空気中にて、１６０〜２００℃、好ましくは、１７０〜１９０℃の温度で露光後加熱する。この後、現像し、かくして、得られた所望のパターンをイミド化するために、更に、加熱する。この加熱温度は、通常、３００〜４００℃の範囲であり、真空下又は窒素雰囲気下で脱溶剤と硬化反応を行う。このようにして、ポリイミド樹脂からなるパターンを得ることができる。このポリイミド樹脂の膜厚は、感光性ポリイミド樹脂前駆体組成物の固形分濃度、粘度、成膜条件等によって制御することができる。
【００５７】
感光性ポリイミド樹脂前駆体組成物を基材の表面に塗布する方法は、特に限定されるものではなく、例えば、スピンコート法やキャスティング法等の一般的な成膜方法を用いることができる。また、上記現像に用いる現像液としては、通常、アルカリ性水溶液が用いられる。
【００５８】
このようにして、基材上に所望のパターンを形成することにより、光導波路等の光部品を作製することができる。そして、例えば、上記光導波路では、このようにして得られたパターン上に、別のポリイミド樹脂からなるオーバークラッド層を形成して、埋め込み型の光導波路構造とすることも可能である。また、フレキシブルな光導波路を得る場合には、上記基材又はオーバークラッド層をエッチング等によって除去すればよい。
【００５９】
かくして、本発明によれば、上述した感光性ポリイミド樹脂前駆体組成物を用いて、パターンを有するポリイミド樹脂を生成させることによって、無色透明で大面積の光導波路を一括して、低コストで製造することができる。
【００６０】
本発明による光導波路としては、例えば、直線光導波路、曲がり光導波路、多層導波路、交差光導波路、Ｙ分岐光導波路、スラブ光導波路、マッハツェンダー型光導波路、ＡＷＧ型光導波路、グレーティング、光導波路レンズ等を挙げることができる。そして、これら光導波路を用いた光素子としては、波長フィルタ、光スイッチ、光分岐器、光合波器、光合分波器、光アンプ、波長変換器、波長分割器、光スプリッタ、方向性結合器、更には、レーザダイオードやフォトダイオードをハイブリッド集積した光伝送モジュール等を挙げることができる。また、従来の電気配線板上に本発明による導波路を形成することもできる。
【００６１】
次に、本発明による感光性ポリイミド樹脂前駆体組成物を用いた光導波路の製造方法について説明する。
【００６２】
本発明による光導波路の製造方法は、感光性ポリイミド樹脂前駆体組成物の感光性を利用して、直接にパターン形成を行う以外は、一般の光導波路の製造方法と同じであり、従って、同様の方法で平面光導波路、リッジ型光導波路、埋め込み型光導波路等を製造することができる。本発明による感光性ポリイミド樹脂前駆体組成物は、コア層形成材料、アンダークラッド層形成材料、オーバークラッド層形成材料のいずれにも、また、同時にも適用することが可能である。コア層形成材料とクラッド層形成材料に同時に用いる際には、用いるテトラカルボン酸二無水物やジアミンを変更したり、また、それらの共重合組成比を変更する等の方法によって、例えば、シングルモード導波路を作製する場合には、両者の屈折率に０．２〜１．０％程度の屈折率の差をもたせるようにすればよい。
【００６３】
光導波路においては、コア層はクラッド層よりも屈折率が高いことが必要である。通常、両者の比屈折率差Δは、シングルモードの場合、０．２〜１．０％程度あればよい。ここに、比屈折率差Δは、ｎ（コア）をコアの屈折率とし、ｎ（クラッド）をクラッドの屈折率とするとき、
Δ＝（（ｎ（コア）−ｎ（クラッド））／ｎ（コア）））×１００（％）
で表される。
【００６４】
このようにポリイミド樹脂の屈折率を調整する方法としては、例えば、分子内にフッ素原子を有するテトラカルボン酸二無水物又は分子内にフッ素原子を有するジアミンを用いて、ポリイミド樹脂の前駆体であるポリアミド酸を製造し、これより屈折率の低いポリイミド樹脂を得、これを用いて、ポリイミド樹脂の屈折率を下げる方法を挙げることができる。そして、これらの含有比率を調整することによって、屈折率差をを適宜に調整することができる。
【００６５】
本発明の光導波路においては、このように、コア層には、本発明による感光性ポリイミド樹脂前駆体組成物から得られるポリイミド樹脂が用いられるが、アンダークラッド層とオーバークラッド層は、コア層よりも屈折率が低い材料であれば、ポリイミド樹脂に限られるものではなく、他の樹脂材料を用いることができる。しかし、耐熱性の点から、コア層は勿論、クラッド層においても、ポリイミド樹脂を材料として用いることが好ましい。
【００６６】
以下に、光導波路の一例として埋め込み型光導波路の製造方法を図面を用いて説明する。図３（Ａ）に示すように、基板１上にこの基板よりも屈折率の高いポリイミド樹脂を与える感光性ポリイミド樹脂前駆体組成物を塗布し、乾燥させて、感光性ポリイミド樹脂前駆体からなる樹脂膜２を形成する。次いで、図３（Ｂ）に示すように、所望のパターンが得られるように、上記樹脂膜２にガラスマスク３を載置し、上方から紫外線を照射する。そして、露光後加熱を行った後、現像液を用いて、現像を行って、所定のパターンに加工した後、加熱、硬化（イミド化）させることによって、図３（Ｃ）に示すように、ポリイミド樹脂からなるパターンをコア層４として形成する。次に、図３（Ｄ）に示すように、上記コアパターン層４上に上記コアパターン層４よりも屈折率の低い材料からなるオーバークラッド層５を形成することによって、埋め込み型光導波路を得ることができる。
【００６７】
このような埋め込み型光導波路構造の具体例として、例えば、図４（Ａ）から（Ｃ）に示すように、基板１上にＹ字状のパターンを有するコア層４を備え、このコア層をオーバークラッド層５で包含してなるＹ分岐型光導波路を挙げることができる。
【００６８】
更に、他の形態の光導波路の作製方法を図面を用いて説明する。図５（Ａ）に示すように、先ず、最終工程でのエッチングが可能であり、且つ、後述するアンダークラッド層との剥離が可能な材質からなる基板６を準備する。次に、図５（Ｂ）に示すように、この基板６上にアンダークラッド層７を形成する。更に、図５（Ｃ）に示すように、このアンダークラッド層７上に、このアンダークラッド層よりも屈折率の高いポリイミド樹脂を与える本発明の感光性ポリイミド樹脂前駆体組成物からなる樹脂膜８を形成する。次いで、上述した埋め込み型光導波路の製造方法と同様にして、所望のパターンが得られるように、上記樹脂膜８にガラスマスクを載置して、その上方から紫外線を照射し、露光後加熱した後、現像液を用いて現像を行い、所定のパターンに加工した後、加熱し、硬化（イミド化）させることによって、図５（Ｄ）に示すように、ポリイミド樹脂からなるパターンとしてコア層９を形成する。次に、図５（Ｅ）に示すように、上記コア層９上にこのコア層よりも屈折率の低い材料からなるオーバークラッド層１０を形成する。この後、前記基板６をエッチング除去することによって、図５（Ｆ）に示すように、リジッドな基板が除去されたフレキシブル光導波路を得ることができる。
【００６９】
このようなフレキシブル光導波路の製造において、上記基板６の材質としては、上記エッチング除去が可能となる条件を有するものであれば特に限定するものではなく、例えば、金属、無機材料、有機フィルム等が用いられる。
【００７０】
また、上記アンダークラッド層７の形成材料とオーバークラッド層１０の形成材料とは同じであっても異なっていてもよい。更に、これらのクラッド層の形成材料として、本発明の感光性ポリイミド前駆体前駆体から感光剤を除いたものを用いてもよい。
【００７１】
【実施例】
以下に比較例と共に実施例を挙げて本発明を説明するが、本発明はこれら実施例により何ら限定されるものではない。
【００７２】
実施例１
窒素雰囲気下、５００ｍＬ容量セパラブルフラスコ内で２，２−ビス（４−アミノフェニル）へキサフルオロプロパン（ＢＡＡＦ）１６．７ｇ（０．０５モル）をＮ，Ｎ−ジメチルアセトアミド（ＤＭＡｃ）１５５．６ｇに溶解させた。攪拌しながら、この溶液に２，２−ビス（３，４−ジカルボキシフェニル）へキサフルオロプロパン二無水物（６ＦＤＡ）２２．２ｇ（０．０５モル）を加えた後、室温で２４時間攪拌して、ポリアミド酸溶液を調製した。
【００７３】
次に、このポリアミド酸溶液に前記感光剤（ＥＤＨＰ）０．０１９ｇ（ポリアミド酸溶液のポリアミド酸（固形分）１００重量部に対して０．０５重量部）と重量平均分子量５００のポリエチレングリコールジメチルエーテル５．８ｇ（ポリアミド酸溶液のポリアミド酸１００重量部に対して１５重量部）とを加えて、感光性ポリイミド樹脂前駆体組成物を溶液として得た。
【００７４】
厚み１．０ｍｍの合成石英ガラス基板上に上記感光性ポリイミド樹脂前駆体組成物の溶液をスピンコート法にて塗布し、９０℃で約１５分間、乾燥させて、上記感光性ポリイミド樹脂前駆体組成物からなる樹脂膜を形成した。この樹脂膜の上に７μｍのライン幅を有する長さ７０ｍｍのパターンが５０μｍピッチで描かれたガラスマスクを載置して、上方から１０ｍＪ／ｃｍ² の紫外線を照射した後、１７０℃で１０分間加熱（露光後加熱）した。次いで、テトラメチルアンモニウムハイドロオキサイド１．５重量％水溶液を現像液として用いて、３５℃で現像し、水でリンスして、所定のパターンからなるコア層を形成した。その後、真空雰囲気下、３８０℃で２時間加熱して、コア層から溶媒を除去すると共に、ポリアミド酸のイミド化（硬化）を完結させた。このようにして得られたポリイミド樹脂のパターンからなるコア層の厚みを接触式表面粗さ計で測定したところ、６．８μｍであった。
【００７５】
このコア層の上にオーバークラッド層を形成するために、別に、トリフルオロメチルピロメリット酸二無水物と２，２’−ビス（トリフルオロメチル）−４，４’−ジアミノジフェニルを溶剤中、等モル比にて反応させて、上記コア層のポリイミド樹脂よりも屈折率の小さいポリイミド樹脂を与えるポリアミド酸溶液を調製した。
【００７６】
上記コア層の上にこのポリアミド酸溶液をスピンコート法にて塗工した後、真空雰囲気下で３８０℃で２時間加熱して、オーバークラッド層を形成し、かくして、埋め込み型の光導波路を得た。この光導波路の端面処理を行った後、波長１３００ｎｍの光を通して、カットバック法で光伝播損失を測定したところ、１．３ｄＢ／ｃｍであった。
【００７７】
実施例２
実施例１において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）２重量部を用いた以外は、実施例１と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例１と同様にして、光伝播損失を測定したところ、１．４ｄＢ／ｃｍであった。
【００７８】
実施例３
実施例１において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）４重量部を用いた以外は、実施例１と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例１と同様にして、光伝播損失を測定したところ、１．６ｄＢ／ｃｍであった。
【００７９】
実施例４
実施例１において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）４重量部とポリエチレングリコールジメチルエーテル１０重量部を用いた以外は、実施例１と同様にして、感光性ポリイミド樹脂前駆体組成物を溶液として得た。
【００８０】
熱酸化膜付きのシリコンウエハ上に上記感光性ポリイミド樹脂前駆体組成物の溶液をスピンコート法にて塗布し、９０℃で約１５分間、加熱して乾燥させて、上記感光性ポリイミド樹脂前駆体組成物からなる厚み８μｍの樹脂膜を形成した。この後、実施例１と同様にして、この樹脂膜にガラスマスクを介して紫外線を照射し、露光後加熱を行った後、現像して、所定のパターンからなる厚み６μｍのコア層を得た。従って、残膜率は７５％であった。ここに、残膜率は、（（光照射前の樹脂膜の厚み（μｍ）−現像後の樹脂膜の厚み（μｍ））／照射前の樹脂膜の厚み（μｍ））×１００（％）で定義される。
【００８１】
実施例５
実施例１において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）４重量部とポリエチレングリコールジメチルエーテル１５重量部を用いた以外は、実施例１と同様にして、感光性ポリイミド樹脂前駆体組成物を溶液として得た。これを用いて、実施例４と同様にして、厚み８μｍの樹脂膜を形成し、この樹脂膜に紫外線を照射し、露光後加熱を行った後、現像して、所定のパターンからなる厚み７．５μｍのコア層を得た。従って、残膜率は９４％であった。
【００８２】
実施例６
実施例１において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）４重量部とポリエチレングリコールジメチルエーテル２０重量部を用いた以外は、実施例１と同様にして、感光性ポリイミド樹脂前駆体組成物を溶液として得た。これを用いて、実施例４と同様にして、厚み８μｍの樹脂膜を形成し、この樹脂膜に紫外線を照射し、露光後加熱を行った後、現像して、所定のパターンからなる厚み６．５μｍのコア層を得た。従って、残膜率は８１％であった。
【００８３】
比較例１
実施例１において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）４重量部のみを用いた以外は、実施例１と同様にして、感光性ポリイミド樹脂前駆体組成物を溶液として得た。これを用いて、実施例４と同様にして、厚み８μｍの樹脂膜を形成し、この樹脂膜に紫外線を照射し、露光後加熱を行った後、現像して、所定のパターンからなる厚み１．５μｍのコア層を得た。従って、残膜率は１９％であった。
【００８４】
比較例２
実施例１において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）４重量部とポリエチレングリコールジメチルエーテル６０重量部を用いた以外は、実施例１と同様にして、感光性ポリイミド樹脂前駆体組成物を溶液として得た。これを用いて、実施例４と同様にして、厚み８μｍの樹脂膜を形成した。
【００８５】
この樹脂膜に実施例４と同様にして紫外線を照射し、露光後加熱を行った後、樹脂膜を観察したところ、相分離が起こっていることが確認された。この樹脂膜の現像を行ったが、露光部と未露光部との間にコントラストを得ることができず、所要のパターンを得ることができなかった。
【００８６】
実施例７
窒素雰囲気下、３００ｍＬ容量のセパラブルフラスコ内で２，２’−ジフルオロベンジジン（ＦＢＺ）８．８１ｇ（０．０４モル）をＮ，Ｎ−ジメチルアセトアミド（ＤＭＡｃ）７９．７ｇに溶解させた。この溶液に攪拌しながら、２，２−ビス（３，４−ジカルボキシフェニル）へキサフルオロブロパン二無水物（６ＦＤＡ）１７．８ｇ（０．０４モル）を加えた後、室温で２４時間攪拌して、ポリアミド酸溶液を得た。
【００８７】
このポリアミド酸溶液のポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）２重量部と重量平均分子量５００のポリエチレングリコールジメチルエーテル１５重量部とを加えて、感光性ポリイミド樹脂前駆体組成物を溶液として得た。
【００８８】
厚み１．０ｍｍの合成石英ガラス基板上に上記感光性ポリイミド樹脂前駆体組成物の溶液をスピンコート法にて塗布し、９０℃で約１５分間、加熱し、乾燥させて、上記感光性ポリイミド樹脂前駆体組成物からなる樹脂膜を形成させた。この樹脂膜の上に６μｍのライン幅を有する長さ７０ｍｍのパターンが１００μｍピッチで描かれたガラスマスクを載置して、上方から全面に１０ｍＪ／ｃｍ² の紫外線を照射し、その後、１７０℃で１０分間加熱した。このようにして得られた露光後の樹脂膜の厚みは８．０μｍであった。
【００８９】
次いで、テトラメチルアンモニウムハイドロオキサイドを含むエタノール／アルカリ性水溶液を現像液として用いて、３５℃で現像した後、水でリンスして、所要のパターンを有するコア層を形成した。このようにして、現像によって得られた樹脂膜の厚みは７．０μｍであった。
【００９０】
その後、真空雰囲気下で３８０℃で２時間加熱して、コア層から溶媒を除去すると共に、ポリアミド酸のイミド化を完結させた。このようにしてポリイミド樹脂のパターンからなるコア層の厚みを接触式表面粗さ計で測定したところ、６．３μｍであった。
【００９１】
このコア層の上にオーバークラッド層を形成するために、別に、２，２−ビス（３，４−ジカルボキシフェニル）ヘキサフルオロプロパン二無水物（６ＦＤＡ）と２，２−ビス（４−アミノフェニル）ヘキサフルオロプロパン（ＢＡＡＦ）を溶剤中、等モル比にて反応させて、上記コア層のポリイミド樹脂よりも屈折率の小さいポリイミド樹脂を与えるポリアミド酸溶液を調製した。
【００９２】
上記コア層の上に上記ポリアミド酸溶液をスピンコート法にて塗工した後、真空雰囲気下で３８０℃で２時間加熱して、オーバークラッド層を形成し、かくして、埋め込み型の光導波路を得た。この光導波路の端面処理を行った後、波長１３００ｎｍの光を通して、カットバック法で光伝播損失を測定したところ、０．７ｄＢ／ｃｍであった。
【００９３】
実施例８
実施例７において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）４重量部を用いた以外は、実施例７と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例７と同様にして、光伝播損失を測定したところ、１．１ｄＢ／ｃｍであった。
【００９４】
実施例９
実施例７において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）０．５重量部を用いた以外は、実施例７と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例７と同様にして、光伝播損失を測定したところ、０．６ｄＢ／ｃｍであった。
【００９５】
実施例１０
実施例７において、ポリアミド酸（固形分）１００重量部に対して、溶解調整剤として、ポリエチレングリコールジメチルエーテルに代えて、重量平均分子量２００のポリエチレングリコール２０重量部を用いた以外は、実施例７と同様にして、感光性ポリイミド樹脂前駆体組成物を溶液として得た。この感光性ポリイミド樹脂前駆体組成物の溶液を用いた以外は、実施例７と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例７と同様にして、光伝播損失を測定したところ、０．７ｄＢ／ｃｍであった。
【００９６】
比較例３
実施例７において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）６重量部を用いた以外は、実施例７と同様にして、感光性ポリイミド樹脂前駆体組成物を溶液として得た。実施例７と同様にして、この感光性ポリイミド樹脂前駆体組成物の溶液を用いて、埋め込み型の光導波路を作製した。この光導波路について、実施例７と同様にして、光伝播損失を測定したところ、３．０ｄＢ／ｃｍであった。
【００９７】
比較例４
実施例７において、溶解調整剤を用いなかった以外は、実施例７と同様にして、感光性ポリイミド樹脂前駆体組成物を溶液として得た。この感光性ポリイミド樹脂前駆体組成物の溶液を用いて、実施例７と同様にして、ポリイミド樹脂からなるパターンを形成しようとしたが、現像工程においてコントラストが不十分であって、得られたコア層の膜厚は２μｍであった。
【００９８】
このようにして得られたコア層を用いて、実施例７と同様にして、光導波路を作製した。この光導波路について、実施例７と同様にして、カットバック法で光伝播損失を測定しようとしたが、光は導波しなかった。
【００９９】
実施例１１
窒素雰囲気下、５００ｍＬ容量セパラブルフラスコ内で２，２’−ビス（トリフルオロメチル）−４，４’−ジアミノビフェニル（ＴＦＭＢ）１６．０ｇ（０．０５モル）をＮ，Ｎ−ジメチルアセトアミド（ＤＭＡｃ）１５２．８ｇに溶解させた。攪拌しながら、この溶液に２，２−ビス（３，４−ジカルボキシフェニル）へキサフルオロブロパン二無水物（６ＦＤＡ）２２．２ｇ（０．０５モル）を加えた後、室温で２４時間攪拌して、ポリアミド酸溶液を調製した。
【０１００】
次に、このポリアミド酸溶液のポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）１．０重量部（０．３８ｇ）と重量平均分子量５００のポリエチレングリコールジメチルエーテル１５重量部（５．７３ｇ）とを加えて、感光性ポリイミド樹脂前駆体組成物を溶液として得た。
【０１０１】
厚み１．０ｍｍの合成石英ガラス基板上に上記ポリアミド酸溶液をスピンコート法にて塗布し、９０℃で約１５分間乾燥させた後、真空雰囲気下、３８０℃で２時間加熱して、ポリアミド酸を硬化（イミド化）させた。このようにして得られたポリイミドの膜厚は１０μｍであった。このポリイミド膜を光導波路のアンダークラッド層とした。
【０１０２】
次に、このアンダークラッド層上に上記感光性ポリイミド樹脂前駆体組成物Ａをスピンコート法に塗布し、９０℃で約１５分間乾燥させて、上記感光性ポリイミド樹脂前駆体組成物からなる樹脂膜を形成した。この樹脂膜の上に８μｍのライン幅を有する長さ７０ｍｍのパターンが５０μｍピッチで描かれたガラスマスクを載置して、上方から１０ｍＪ／ｃｍ² の紫外線を照射した後、１８０℃で１０分間加熱（露光後加熱）した。次いで、テトラメチルアンモニウムハイドロオキサイド５重量％水溶液を現像液として用いて、３５℃で現像し、水でリンスして、所定のパターンからなる光導波路のコア層を形成した。その後、真空雰囲気下、３６０℃で２時間加熱して、コア層から溶媒を除去すると共に、ポリアミド酸のイミド化（硬化）を完結させた。このようにして得られたポリイミド樹脂のパターンからなるコア層の厚みを接触式表面粗さ計で測定したところ、６．５μｍであった。
【０１０３】
このコア層の上に上記ポリアミド酸溶液をスピンコート法にて塗工した後、真空雰囲気下、３８０℃で２時間加熱して、２０μｍ厚のオーバークラッド層を形成し、かくして、埋め込み型の光導波路を得た。この光導波路の端面処理をダイシング装置を用いて行った後、波長１５５０ｎｍの光を通して、カットバック法で光伝播損失を測定したところ、０．８ｄＢ／ｃｍであった。
【０１０４】
実施例１２
窒素雰囲気下、５００ｍＬ容量セバラブルフラスコ内で２，２’−ジフルオロベンジジン（ＦＢＺ）１１．０ｇ（０．０５モル）をＮ，Ｎ−ジメチルアセトアミド（ＤＭＡｃ）１３２．８ｇに溶解させた。攪拌しながら、この溶液に２，２−ビス（３，４−ジカルボキシフェニル）へキサフルオロプロパン二無水物（６ＦＤＡ）２２．２ｇ（０．０５モル）を加えた後、室温で２４時間攪拌して、ポリアミド酸溶液を調製した。
【０１０５】
次に、このポリアミド酸溶液にポリアミド酸（固形分）１００重量部に対して感光剤（ＥＤＨＰ）１．０重量部と重量平均分子量５００のポリエチレングリコールジメチルエーテル１５重量部とを加えて、感光性ポリイミド樹脂前駆体組成物を溶液として得た。
【０１０６】
コア層の形成のためにこの感光性ポリイミド樹脂前駆体組成物を用いた以外は、実施例１１と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例１１と同様にして、光伝播損失を測定したところ、０．９ｄＢ／ｃｍであった。
【０１０７】
実施例１３
窒素雰囲気下、５００ｍＬ容量セパラブルフラスコ内で２，２’−ビス（トリフルオロメチル）−４，４’−ジアミノビフェニル（ＴＦＭＢ）８．０ｇ（０．０２５モル）と４，４’−オキシジアニリン（ＯＤＡ）５．０ｇ（０．０２５モル）をＮ，Ｎ−ジメチルアセトアミド（ＤＭＡｃ）１４．０８ｇに溶解させた。攪拌しながら、この溶液に２，２−ピス（３，４−ジカルボキシフェニル）へキサフルオロプロパン二無水物（６ＦＤＡ）２２．２ｇ（０．０５モル）を加えた後、室温で２４時間攪拌して、ポリアミド酸溶液を調製した。
【０１０８】
次に、このポリアミド酸溶液にポリアミド酸（固形分）１００重量部に対して感光剤（ＥＤＨＰ）１．０重量部と重量平均分子量５００のポリエチレングリコールジメチルエーテル１５重量部とを加えて、感光性ポリイミド樹脂前駆体組成物を溶液として得た。
【０１０９】
コア層の形成のために上記感光性ポリイミド樹脂前駆体組成物を用いた以外は、実施例１１と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例１と同様にして、光伝播損失を測定したところ、０．９ｄＢ／ｃｍであった。
【０１１０】
実施例１４
窒素雰囲気下、５００ｍＬ容量セパラブルフラスコ内で２，２’−ビス（トリフルオロメチル）−４，４’−ジアミノビフェニル（ＴＦＭＢ）１６．０ｇ（０．０５モル）をＮ，Ｎ−ジメチルアセトアミド（ＤＭＡｃ）１３０．２ｇに溶解させた。攪拌しながら、この溶液に２，２−ビス（３．４−ジカルボキシフェニル）へキサフルオロプロパン二無水物（６ＦＤＡ）１１．１ｇ（０．０２５モル）とピロメリット酸二無水物（ＰＭＤＡ）５．４５ｇ（０．０２５モル）を同時に加えた後、室温で２４時間攪拌して、ポリアミド酸溶液を調製した。
【０１１１】
次に、このポリアミド酸溶液にポリアミド酸（固形分）１００重量部に対して感光剤（ＥＤＨＰ）１．０重量部と重量平均分子量５００のポリエチレングリコールジメチルエーテル１５重量部とを加えて、感光性ポリイミド樹脂前駆体組成物を溶液として得た。
【０１１２】
コア層の形成のために上記感光性ポリイミド樹脂前駆体組成物を用いた以外は、実施例１１と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例１１と同様にして、光伝播損失を測定したところ、０．８ｄＢ／ｃｍであった。
【０１１３】
実施例１５
窒素雰囲気下、５００ｍＬ容量セパラブルフラスコ内で２，２’−ビス（トリフルオロメチル）−４，４’−ジアミノビフェニル（ＴＦＭＢ）１６．０ｇ（０．０５モル）Ｎ，Ｎ−ジメチルアセトアミド（ＤＭＡｃ）１３．９４ｇに溶解させた。攪拌しながら、この溶液に２，２−ビス（３，４−ジカルボキシフェニル）へキサフルオロプロパン二無水物（６ＦＤＡ）１１．１ｇ（０．０２５モル）とビス（３，４−ジカルボキシフェニル）エーテル酸二無水物（ＯＰＤＡ）７．７６ｇ（０．０２５モル）を同時に加えた後、室温で２４時間槽攪拌て、ポリアミド酸溶液を調製した。
【０１１４】
次に、このポリアミド酸溶液にポリアミド酸（固形分）１００重量部に対して感光剤（ＥＤＨＰ）１．０重量部と重量平均分子量５００のポリエチレングリコールジメチルエーテル１５重量部とを加えて、感光性ポリイミド樹脂前駆体組成物を溶液として得た。
【０１１５】
コア層の形成ために上記感光性ポリイミド樹脂前駆体組成物を用いた以外は、実施例１１と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例１１と同様にして、光伝播損失を測定したところ、１．１ｄＢ／ｃｍであった。
【０１１６】
実施例１６
窒素雰囲気下、５００ｍＬ容量セパラブルフラスコ内で２，２’−ビス（トリフルオロメチル）−４，４’−ジアミノビフェニル（ＴＦＭＢ）１６．０ｇ（０．０５モル）Ｎ，Ｎ−ジメチルアセトアミド（ＤＭＡｃ）１３７．８ｇに溶解させた。攪拌しながら、この溶液に２，２−ビス（３，４−ジカルボキシフェニル）へキサフルオロプロバン二無水物（６ＦＤＡ）１１．１ｇ（０．０２５モル）と３，３’４，４’−ビフェニルテトラカルボン酸二無水物（ＢＰＤＡ）７．４ｇ（０．０２５モル）を同時に加えた後、室温で２４時間攪拌して、ポリアミド酸溶液を調製した。
【０１１７】
次に、このポリアミド酸溶液にポリアミド酸（固形分）１００重量部に対して感光剤（ＥＤＨＰ）１．０重量部と重量平均分子量５００のポリエチレングリコールジメチルエーテル１５重量部とを加えて、感光性ポリイミド樹脂前駆体組成物を溶液として得た。
【０１１８】
コア層の形成のために上記感光性ポリイミド樹脂前駆体組成物をを用いた以外は、実施例１１と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例１１と同様にして、光伝播損失を測定したところ、１．１ｄＢ／ｃｍであった。
【０１１９】
実施例１７
窒素雰囲気下、５００ｍＬ容量セパラブルフラスコ内で２，２’−ビス（トリフルオロメチル）−４，４’−ジアミノビフェニル（ＴＦＭＢ）８．０ｇ（０．０２５モル）と２，２−ビス（４−アミノフェニル）へキサフルオロプロパン（ＢＩＳ−Ａ−ＡＦ）８．４ｇ（０．０２５モル）をＮ，Ｎ−ジメチルアセトアミド）ＤＭＡｃ）１５４．３ｇに溶解させた。攪拌しながら、この溶液に２，２−ビス（３，４−ジカルボキシフェニル）へキサフルオロプロパン二無水物（６ＦＤＡ）２２．２ｇ（０．０５モル）を加えた後、室温で２４時間攪拌して、ポリアミド酸溶液を調製した。
【０１２０】
アンダークラッド層とオーバークラッド層の形成に上記ポリアミド酸ワニスを用いると共に、コア層の形成のために、実施例１１において調製した感光性ポリイミド樹脂前駆体組成物Ａを用いた以外は、実施例１１と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例１１と同様にして、光伝播損失を測定したところ、０．９ｄＢ／ｃｍであった。
【０１２１】
実施例１８
実施例１１において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）３重量部を用いた以外は、実施例１１と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例１１と同様にして、光伝播損失を測定したところ、１．１ｄＢ／ｃｍであった。
【０１２２】
実施例１９
実施例１１において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）０．０５重量部を用いた以外は、実施例１１と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例１１と同様にして、光伝播損失を測定したところ、０．８ｄＢ／ｃｍであった。
【０１２３】
実施例２０
実施例１１において、ポリエチレングリコールジメチルエーテルに代えて、重量平均分子量５００のポリプロピレングリコールジメチルエーテルを用いた以外は、実施例１１と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例１１と同様にして、光伝播損失を測定したところ、０．８ｄＢ／ｃｍであった。
【０１２４】
実施例２１
実施例１１において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）１．０重量部と重量平均分子量５００のポリエチレングリコールジメチルエーテル３０重量部とを用いた以外は、実施例１１と同様にして、感光性ポリイミド樹脂前駆体組成物を溶液として得た。
【０１２５】
厚み１．０ｍｍの合成石英ガラス基板上に実施例１１にて調製したポリアミド酸溶液をスピンコート法にて塗布し、９０℃で約１５分間乾燥させた後、真空雰囲気下、３６０℃で２時間加熱して、硬化（イミド化）させた。このようにして得られたポリイミドの膜厚は１０μｍであった。これを光導波路のアンダークラッド層とした。
【０１２６】
次に、このアンダークラッド層上に上記感光性ポリイミド樹脂前駆体組成物をスピンコート法にて塗布し、９０℃で約１５分間、乾燥させて、上記感光性ポリイミド樹脂前駆体細成物からなる樹脂膜を形成した。この樹脂膜の上に８μｍのライン幅を有する長さ７０ｍｍのパターンが５０μｍピッチで描かれたガラスマスクを載置して、上方から１０ｎＪ／ｃｍ² の紫外線を照射した後、１８０℃で１０分間加熱（露光後加熱）した。次いで、テトラメチルアンモニウムハイドロオキサイド５重量％水溶液を現像液として用いて、３５℃で現像し、水でリンスして、所定のパターンからなる光導波路のコア層を形成した。コア層の残膜率は８０％であった。また、コア層の断面の形状を調べたところ、底角８８〜９０゜の方形であった。この後、真空雰囲気下、３６０℃で２時間加熱して、コア層から溶媒を除去すると共に、ポリアミド酸の硬化（イミド化）を完結させた。
【０１２７】
上記コア層の上に前記アンダークラッド層の形成に用いたのと同じポリアミド酸溶液をスピンコート法にて塗工した後、真空雰囲気下で３６０℃で２時間加熱して、２０μｍ厚のオーバークラッド層を形成し、かくして、埋め込み型の光導波路を得た。この光導波路の端面処理をダイシング装置を用いて行った後、波長１５５０ｎｍの光を通して、カットバック法で光伝播損失を測定したところ、０．５ｄＢ／ｃｍであった。
【０１２８】
実施例２２
実施例１１において、溶解調整剤として、ポリエチレングリコールジメチルエーテルに代えて、重量平均分子量３００のポリプロピレングリコール３０重量部を用いた以外は、実施例１１と同様にして、ポリアミド酸溶液と感光性ポリイミド樹脂前駆体組成物をそれぞれ調製し、これらを用いて、実施例１１と同様にして、光導波路を作製し、残膜率、コア層の底角及び得られた光導波路の伝播損失を測定したところ、それぞれ８５％、８８〜９０°及び０．５ｄＢ／ｃｍであった。
【０１２９】
実施例２３
実施例１１において、溶解調整剤として、ポリエチレングリコールジメチルエーテルに代えて、重量平均分子量４００のポリプロピレングリコールジフェニルエーテル３０重量部を用いた以外は、実施例１１と同様にして、ポリアミド酸溶液と感光性ポリイミド樹脂前駆体組成物をそれぞれ調製し、これらを用いて、実施例１１と同様にして、光導波路を作製し、現像残膜率、コア層の底角及び得られた光導波路の伝播損失を測定したところ、それぞれ８０％、８８〜９０°及び０．５ｄＢ／ｃｍであった。
【０１３０】
比較例５
実施例１１において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）７重量部を用いた以外は、実施例１１と同様にして、埋め込み型の光導波路を得た。この光導波路について、実施例１１と同様にして、光伝播損失を測定したところ、２．４ｄＢ／ｃｍであった。
【０１３１】
比較例６
実施例１１において、ポリアミド酸（固形分）１００重量部に対して、感光剤（ＥＤＨＰ）０．００５重量部を用いた以外は、実施例１１と同様にして、埋め込み型の光導波路を得ることを試みたが、現像時に露光部と未露光部でコントラストを得ることができず、光導波路のコアバターンが形成できなかった。
【０１３２】
比較例７
実施例１１において、ポリアミド酸（固形分）１００重量部に対して、ポリエチレングリコールジメチルエーテル６０重量部を用いた以外は、実施例１１と同様にして、埋め込み型の光導波路を得ることを試みたが、露光後加熱の段階でポリアミド酸膜内で相分離が生じており、目的とする解像度のパターンを得ることができず、光導波路のコアバターンが形成できなかった。
【０１３３】
比較例８
実施例１１において、ポリアミド酸（固形分）１ 0 0重量部に対して、重量平均分子量５００のポリエチレングリコールジメチルエーテル３重量部を用いた以外は、実施例１１と同様にして、埋め込み型の光導波路を得ようとしたが、現像時に露光部と未露光部との間でコントラストを得ることができず、光導波路のコアパターンが形成できなかった。
【０１３４】
比較例９
厚み１．０ｍｍの合成石英ガラス基板上に実施例１１と同じポリアミド酸溶液をスピンコートにて塗布し、９０℃で約１５分間乾燥させた後、真空雰囲気下、３６０℃で２時間加熱して、ポリアミド酸を硬化（イミド化）させた。このようにして得られたポリイミドの膜厚は１０μｍであった。このポリイミド膜をアンダークラッド層とした。
【０１３５】
次に、このアンダークラッド層上に実施例１１と同じ感光性ポリイミド樹脂前駆体組成物をスピンコート法にて塗布し、９０℃で約１５分間乾燥させて、上記感光性ポリイミド樹脂前駆体組成物からなる樹脂膜を形成した。更に、真空雰囲気下、３６０℃で２時間加熱して、コア層から溶媒を除去すると共に、ポリアミド酸の硬化（イミド化）を完結させた。
【０１３６】
次に、従来より知られている酸素プラズマを用いた反応性イオンエッチング法にて、８μｍのライン幅を有する長さ７０ｍｍのパターンが５０μｍピッチで描かれた所定のパターンが得られるようにコア層を加工した。このようにして得られたコア層の下に上記アンダークラッド層の形成に用いたのと同じボリアミド酸溶液をスピンコート法にて塗布した後、真空雰囲気下、３６０℃で２時間加熱して、２０μｍ厚のオーバークラッド層を形成し、かくして、埋め込み型の光導波路を得た。この光導波路の端面処理をダイシング装置を用いて行った後、波長１５５０ｎｍの光を通して、カットバック法で光伝播損失を測定したところ、１．２ｄＢ／ｃｍであった。
【０１３７】
【発明の効果】
以上のように、本発明の感光性ポリイミド樹脂前駆体組成物は、従来のものに比べて、感光剤の配合量を少量としながら、溶解調整剤を配合したものであるので、その膜に少量の紫外線照射によって露光させた後、露光後加熱し、現像すれば、高いコントラストにて所要のパターンからなるポリイミド樹脂を得ることができる。
【０１３８】
特に、ポリイミド樹脂の前駆体であるポリアミド酸として、それぞれフッ素原子を有するテトラカルボン酸二無水物とジアミンとから得られるものを用いることによって、実質的に着色がなく、透明で、耐熱性を有し、光学用樹脂として好適に用いることができるポリイミド樹脂を得ることができる。従って、例えば、このようなポリイミド樹脂をコア層として利用することによって、光損失の少ない光導波路を得ることができる。
【図面の簡単な説明】
【図１】ポリイミド樹脂膜のウェットプロセスによって得られるパターンの通常の断面形状を示す。
【図２】本発明によるポリイミド樹脂膜のウェットプロセスによって得られるパターンの方形の断面形状を示す。
【図３】（Ａ）から（Ｄ）は、本発明による埋め込み型光導波路の製造工程を示す図である。
【図４】（Ａ）は分岐型光導波路を示す斜視図であり、（Ｂ）はＢ−Ｂ線に沿う断面図であり、（Ｃ）はＣ−Ｃに沿う断面図である。
【図５】（Ａ）から（Ｆ）は、本発明による別の形態の光導波路の製造工程を示す図である。
【符号の説明】
１…基板
２…感光性ポリイミド樹脂前駆体組成物からなる樹脂膜
３…ガラスマスク
４…コア層（コアパターン層）
５…オーバークラッド層
６…基板
７…アンダークラッド層
８…感光性ポリイミド樹脂前駆体組成物からなる樹脂膜
９…コア層
１０…オーバークラッド層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photosensitive polyimide resin precursor composition, an optical polyimide resin obtained therefrom, and an optical waveguide. Specifically, the present invention is a transparent and birefringent index that can be preferably used for optical waveguides, optical waveguide devices, optical integrated circuits, optical wiring boards, and the like widely used in the fields of optical communication, optical information processing, and other general optics. A photosensitive polyimide resin precursor composition that gives a small optical polyimide resin, an optical polyimide resin obtained from such a photosensitive polyimide resin precursor composition, and in particular such an optical polyimide resin as a core layer It is related with the optical waveguide obtained by using.
[0002]
[Prior art]
With the practical application of optical communication systems through the development of optical fibers, development of a wide variety of optical communication devices using optical waveguide structures is required. In general, characteristics required for the optical waveguide material include a small light propagation loss, heat resistance and moisture resistance, and control of the refractive index and film thickness. In order to meet these requirements, conventionally, a silica-based optical waveguide has been mainly studied.
[0003]
However, for the construction of optical fiber networks such as WDM communications, it is essential to reduce the cost of manufacturing various devices. Therefore, polymer materials that are mass-productable and that can be processed in large areas are used as optical waveguide materials. In recent years, organic materials such as polymethyl methacrylate, polycarbonate, and polystyrene have been studied. However, such a polymer has a drawback that its range of use is very limited when it is hybrid-integrated with a laser diode, a photodiode or the like, because the heat resistance in the solder reflow process is not sufficient. Here, the polyimide resin-based material has the highest heat resistance among many polymer materials, and has recently attracted attention as an optical waveguide material.
[0004]
Conventionally, an optical circuit made of polyimide resin is generally formed by the following dry process. That is, first, polyamic acid, which is a polyimide resin precursor, is dissolved in a polar solvent such as N, N-dimethylacetamide or N-methyl-2-pyrrolidone to obtain a polyamic acid varnish, which is spin-coated or casted. The substrate is coated on the substrate and heated to remove the solvent, and the polyamic acid is closed and imidized to form a polyimide resin film. Then, selective ion etching (RIE, Reactive lon) using oxygen plasma or the like is performed. Etching) is used to form a pattern.
[0005]
However, according to such a conventional dry process, not only does it take a long time to form an optical circuit, but also the processing area is limited, so the problem of cost reduction has not been solved. Also, according to such a dry process, since the wall surface (side surface) of the pattern to be formed is not flat, scattering loss increases when light is guided to the optical circuit.
[0006]
Furthermore, according to the conventional dry process, after covering the polyimide resin film with a resist layer corresponding to the required pattern, the region not covered with the resist layer is irradiated with ions from above, and the above pattern is obtained by etching. Thereafter, the resist is dissolved and removed to obtain a required pattern made of polyimide resin. Thus, according to such a dry process, since the ion irradiation direction is one direction, the etching proceeds in one direction, and as a result, the obtained pattern has a square cross-sectional shape. However, due to the resolution, adhesion, and material brittleness of the resist, the side surface of the obtained pattern is not smooth, and minute irregularities are observed. When such a pattern is used as the core of an optical waveguide, it is known that the unevenness on the side surface causes light scattering and affects important transmittance of the optical waveguide.
[0007]
On the other hand, as described in JP-A-6-43648, JP-A-7-179604, JP-A-7-234525, etc., a photosensitive compound containing a 1,4-dihydropyridine derivative as a photosensitizer. If the polyimide resin is formed by a wet process using a conductive polyimide resin precursor composition, the above-described problem does not occur. However, for the obtained polyimide resin, a new problem of light loss must be solved.
[0008]
That is, in order to use the polyimide resin by the wet process as an optical waveguide material, the polyimide resin does not absorb the guided light, that is, has a low loss with respect to light, and if necessary, has transparency. It is essential to have.
[0009]
In order to form a polyimide resin by the wet process described above, conventionally, in order to impart photosensitivity to the polyamic acid which is a polyimide resin precursor, the conventional range is 5 to 70 parts by weight with respect to 100 parts by weight of the polyamic acid. In the stage where the photosensitive polyimide resin precursor composition is heated to ring-close and cure (imidize) the polyamic acid, the photosensitive agent is thermally decomposed and obtained. The polyimide resin is colored black.
[0010]
The material used to manufacture the optical waveguide is required to be transparent from the visible light to the near infrared region, and the polyimide resin obtained by the wet process described above is not only in the visible light region but also in the near infrared region. Is partially absorbed, so it is difficult to use as an optical waveguide material.
[0011]
Therefore, as a result of intensive studies to solve the problems in the case where the polyimide resin obtained by the wet process described above is used for optics, the present inventors have studied 1.3 μm band, 1.55 μm band, etc. used as communication wavelengths. It was ascertained that light absorption by the polyimide resin in the near infrared region was caused by C—H bonds in the obtained polyimide resin.
[0012]
That is, in the conventional wet process, according to the description in JP-A-6-43648, 5 parts of the 1,4-dihydropyridine derivative are used as a photosensitizer with respect to 100 parts by weight of polyamic acid which is a precursor of polyimide resin. It mix | blends in the range of -50 weight part, it is set as the photosensitive polyimide resin precursor composition, After light-irradiating this, it heats after exposure, It carries out development, a heating, and hardening (imidation) after that, and polyimide resin The pattern which consists of is formed. However, the present inventors reduced the amount of the photosensitive agent to less than 5 parts by weight with respect to 100 parts by weight of the polyamic acid, thereby decomposing the photosensitive agent in the heating and curing (imidization) stage. It has been found that the coloring of polyimide resin based on can be greatly reduced. In particular, the present inventors significantly reduced the amount of photosensitizer blended in the resulting polyamic acid by introducing fluorine atoms into the raw material for polyamic acid, ie, tetracarboxylic dianhydride and diamine. It was also found that effective photosensitivity can be maintained, and thus a pattern can be formed.
[0013]
Furthermore, the present inventors have thus made polyethylene glycol, polyethylene glycol monomethyl ether, even if the addition amount of the photosensitizer to the polyamic acid obtained from tetracarboxylic dianhydride having a fluorine atom and diamine is small. Formulating at least one glycol (ether) selected from polyethylene glycol dimethyl ether, polyethylene glycol monophenyl ether, polyethylene glycol diphenyl ether, polypropylene glycol, polypropylene glycol monomethyl ether, polypropylene glycol dimethyl ether, polypropylene glycol monophenyl ether and polypropylene glycol diphenyl ether By irradiating the resulting photosensitive polyimide resin precursor composition with light During development, there is a significant difference in solubility in the developer between the exposed part and the unexposed part, so that a high contrast can be obtained when developing the light-irradiated polyimide resin precursor composition, that is, the glycol. It has been found that ether is effective as a dissolution regulator or contrast enhancer.
[0014]
In addition, when the polyimide resin obtained by the wet process of the photosensitive polyimide resin precursor composition described above is used as an optical waveguide material, in particular, when used as a core layer of an optical waveguide, in addition to the problem of optical loss described above, a pattern There is a problem of the cross-sectional shape.
[0015]
Generally, according to a conventional wet process, a polyimide resin film is coated with a resist layer corresponding to a required pattern, and a resin film in a region not covered with the resist layer is dissolved with a developer to form a pattern. obtain. In such a wet process, the etching of the resin film proceeds in the thickness direction of the resin film, and at the same time, also proceeds in the surface direction of the resin film by so-called liquid circulation, and in the finally obtained pattern, Since the pattern width is different between the upper surface and the lower surface of the film, the cross-sectional shape of the obtained pattern is a trapezoid whose base angle α is convex upwards of about 60 to 80 °, as shown in FIG. Absent.
[0016]
In the wet process (development) using the photosensitive polyimide resin precursor composition described above, no resist is used, but pattern formation is performed using the difference in solubility in the developer between the exposed and unexposed areas. Basically, like the pattern formation by a normal wet process, the cross section of the obtained pattern has a trapezoidal shape that is convex upward.
[0017]
Here, the cross-sectional shape of the core layer of the ideal optical waveguide is a circular shape having the best contrast as in the optical fiber. However, in many optical waveguides including a planar lightwave circuit (PLC), it is difficult to make the cross-sectional shape of the core circular due to its manufacturing method. Therefore, as shown in FIG. A square cross-sectional shape is required. This square cross-sectional shape seems promising from the viewpoint of minimizing mode mismatching at the connection with the fiber.
[0018]
Therefore, the present inventors have intensively studied to solve the problem in the case where the polyimide resin obtained by the wet process described above is used for optics, and as a result, by further adjusting the blending amount of the above-described dissolution regulator, In the development after the photosensitive polyimide resin precursor composition is irradiated with ultraviolet rays, heated after exposure, and developed, a significant difference in the solubility in the developer between the exposed portion and the unexposed portion can be caused. A very large contrast can be obtained with the exposed portion. Thus, according to the present invention, a pattern having a square cross-sectional shape as shown in FIG. 2 which has been conventionally difficult to obtain by a wet process of a photosensitive polyimide resin precursor composition, or an aspect in some cases. It has been found that a pattern having a square cross section with a ratio exceeding 1 can be obtained.
[0019]
In this way, the present inventors preferably blend a photosensitizing agent and a dissolution regulator in a polyamic acid obtained from a tetracarboxylic dianhydride having a fluorine atom in the molecule and a diamine to form a photosensitive polyimide. If it is a resin precursor composition, the polyimide resin obtained from this can be used preferably for optical applications. In particular, it has a high degree of transparency required as an optical waveguide material, and according to a preferred embodiment, it is wet. It has been found that a pattern having a square cross section can be obtained by the process, and the present invention has been achieved.
[0020]
[Problems to be solved by the invention]
Accordingly, the present invention has been made to solve various problems including the manufacturing cost of the conventional optical waveguide material, and in particular, to solve the above-described problems in the polyimide resin obtained by the wet process using the conventional photosensitive agent. A photosensitive polyimide resin precursor composition that provides a transparent polyimide resin necessary as an optical waveguide material, a transparent and heat-resistant optical polyimide resin obtained therefrom, and further, a polyimide resin such as this It aims at providing the optical device obtained by using, especially an optical waveguide.
[0021]
[Means for Solving the Problems]
According to the present invention,
(A) polyamic acid obtained from tetracarboxylic dianhydride and diamine;
(B) General formula (I) with respect to 100 parts by weight of this polyamic acid
[0022]
[Chemical 6]

[0023]
(In the formula, Ar represents an aromatic group having a nitro group in the ortho position with respect to the bonding position to the 1,4-dihydropyridine ring; ₁ Represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ₂ , R _Three , R _Four And R _Five Each independently represents a hydrogen atom or an alkyl group having 1 or 2 carbon atoms. )
0.01 part by weight or more and less than 5 parts by weight of a 1,4-dihydropyridine derivative represented by:
(C) at least selected from polyethylene glycol, polyethylene glycol monomethyl ether, polyethylene glycol dimethyl ether, polyethylene glycol monophenyl ether, polyethylene glycol diphenyl ether, polypropylene glycol, polypropylene glycol monomethyl ether, polypropylene glycol dimethyl ether, polypropylene glycol monophenyl ether and polypropylene glycol diphenyl ether A photosensitive polyimide resin precursor composition comprising 5 to 50 parts by weight of one kind of glycol (ether) is provided.
[0024]
Moreover, according to this invention, after irradiating the said photosensitive polyimide resin precursor composition with an ultraviolet-ray, it heats after exposure, develops, and provides the optical polyimide resin obtained by heating. Furthermore, according to the present invention, there is provided an optical waveguide comprising a core layer made of the above-described optical polyimide resin as a cladding layer.
[0025]
In addition to the above, according to the present invention, 0.01 parts by weight or more and less than 5 parts by weight of the 1,4-dihydropyridine derivative with respect to 100 parts by weight of the polyamic acid and the polyamic acid, and a weight average molecular weight of 200 to A photosensitive polyimide resin precursor composition containing 20 to 40 parts by weight of 2000 glycol (ether) is applied on a substrate to form a photosensitive resin film, and after exposure to ultraviolet rays through a mask, exposure There is provided a method for manufacturing an optical waveguide, characterized in that a core layer having a square cross section is formed by post-heating, developing and heating.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
The photosensitive polyimide resin precursor composition according to the present invention comprises a polyamic acid obtained from tetracarboxylic dianhydride and a diamine and a photosensitizer, together with polyethylene glycol, polyethylene glycol monomethyl ether, polyethylene glycol dimethyl ether, polyethylene glycol monophenyl ether, It comprises at least one glycol (ether) selected from polyethylene glycol diphenyl ether, polypropylene glycol, polypropylene glycol monomethyl ether, polypropylene glycol dimethyl ether, polypropylene glycol monophenyl ether and polypropylene glycol diphenyl ether as a dissolution regulator.
[0027]
In the present invention, the tetracarboxylic dianhydride is not particularly limited. For example, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 3,3 ′, 4,4′-benzophenone Examples thereof include tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, and bis (3,4-dicarboxyphenyl) sulfonic dianhydride.
[0028]
However, according to the present invention, the tetracarboxylic dianhydride is particularly preferably one containing a fluorine atom in the molecule (hereinafter referred to as fluorine-substituted tetracarboxylic dianhydride). Examples of such a fluorine-substituted tetracarboxylic dianhydride include 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride and 4,4-bis (3,4-dicarboxy). Trifluorophenoxy) tetrafluorobenzene dianhydride, 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene dianhydride, (trifluoromethyl) biromellitic dianhydride, di (trifluoro Examples include methyl) pyromellitic dianhydride, di (heptafluoropropyl) pyromellitic dianhydride and the like.
[0029]
On the other hand, examples of the diamine include m-phenylenediamine, p-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, and 3,3'-diamino. Diphenylsulfone, 2,2-bis (4-aminophenoxyphenyl) propane, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 2,4-diaminotoluene, Examples include 2,6-diaminotoluene, 4,4′-diaminodiphenylmethane, 4,4′-diamino-2,2′-dimethylbiphenyl, and the like.
[0030]
However, as in the case of tetracarboxylic dianhydride, according to the present invention, the diamine is particularly preferably one containing a fluorine atom in the molecule (hereinafter referred to as fluorine-substituted diamine). Examples of such a fluorine-substituted diamine include 2,2′-bis (trifluoromethoxy) -4,4′-diaminobiphenyl (TFMOB), 3,3′-diamino-5,5′-bis (trifluoro). Methyl) biphenyl, 2,2-bis (4-aminophenyl) hexafluoropropane (BAAF), 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane (HFBAPP), 2,2 '-Bis (trifluoromethyl) -4,4'-diaminobiphenyl (TFMB), 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (BIS-AP-AF), 2,2 -Bis (3-amino-4-methylphenyl) hexafluoropropane (BIS-AT-AF), 2,2'-difluorobenzidine (FBZ), 4,4 Examples include '-bis (aminooctafluoro) biphenyl, 3,5-diaminobenzotrifluoride, 1,3-diamino-2,4,5,6-tetrafluorobenzene.
[0031]
In the present invention, the polyamic acid can be obtained by reacting the tetracarboxylic dianhydride as described above with a diamine according to a conventional method. That is, for example, under a nitrogen atmosphere, a solution in which a diamine is dissolved in an appropriate organic solvent and an equimolar amount of tetracarboxylic dianhydride are added and stirred at room temperature for about 5 to 20 hours. A solution of polyamic acid can be obtained as a viscous solution.
[0032]
The solvent is not particularly limited as long as it is conventionally used for the production of polyamic acid. For example, N, N-dimethylacetamide (DMAc) or N-methyl-2-pyrrolidone (NMP) ) And the like are preferably used, and in particular, DMAc is preferably used because it is not thermally decomposed and has excellent transparency.
[0033]
According to the present invention, among the polyamic acids thus obtained, the following general formula (II)
[0034]
[Chemical 7]

[0035]
(Wherein R ₆ Is represented by the following formulas (IIa), (IIb), (IIc), (IId) and (IIe)
[0036]
[Chemical 8]

[0037]
At least one tetravalent group selected from the tetravalent groups represented by: ₇ Is represented by the following formulas (IIf), (IIg), (IIh) and (IIi)
[0038]
[Chemical 9]

[0039]
And at least one divalent group selected from divalent groups represented by: )
Having a repeating unit represented by
A polyimide resin obtained by using polyamic acid has a low refractive index, and is preferably used because a relative refractive index difference from the clad can be easily adjusted in the case of forming a core layer in an optical waveguide.
[0040]
The photosensitive polyimide resin precursor composition according to the present invention has a general formula (I) based on 100 parts by weight of such a polyamic acid.
[0041]
[Chemical Formula 10]

[0042]
(In the formula, Ar represents an aromatic group having a nitro group in the ortho position with respect to the bonding position to the 1,4-dihydropyridine ring; ₁ Represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ₂ , R _Three , R _Four And R _Five Each independently represents a hydrogen atom or an alkyl group having 1 or 2 carbon atoms. )
1,4-dihydropyridine derivative represented by the formula, with 0.01 parts by weight or more and less than 5 parts by weight as a photosensitizer, and 5 to 50 parts by weight of the glycol (ether) as a dissolution regulator. It is.
[0043]
Specific examples of the photosensitizer include, for example, 1-ethyl-3,5-dimethoxycarbonyl-4- (2-nitrophenyl) -1,4-dihydropyridine, 1-methyl-3,5-dimethoxycarbonyl-4- ( 2-nitrophenyl) -1,4-dihydropyridine, 1-propyl-3,5-dimethoxycarbonyl-4- (2-nitrophenyl) -1,4-dihydropyridine, 1-propyl-3,5-diethoxycarbonyl- 4- (2-nitrophenyl) -1,4-dihydropyridine and the like can be mentioned.
[0044]
However, according to the present invention, among the various photosensitizers described above, 1-ethyl-3,5-dimethoxycarbonyl-4- (2) is particularly preferred because of low cost and light absorption due to C—H bonds. -Nitrophenyl) -1,4-dihydropyridine (hereinafter referred to as EDHP) is preferably used.
[0045]
Such a 1,4-dihydropyridine derivative is obtained by, for example, reacting a substituted benzaldehyde with an alkylpropiolate (propargylic acid alkyl ester) in an amount twice its molar amount and a corresponding primary amine in glacial acetic acid under reflux. (Khim. Geterotsikl. Soed., Pp. 1067-1071, 1982).
[0046]
Such a photosensitizer is used in a range of 0.01 parts by weight or more and less than 5 parts by weight, preferably 0.05 to 2 parts by weight, with respect to 100 parts by weight of the polyamic acid. According to the present invention, if a photosensitive polyimide resin precursor composition is used by using 5 parts by weight or more of a photosensitizing agent with respect to 100 parts by weight of the polyamic acid, the polyimide resin obtained therefrom is in the near infrared region. Absorbs light. However, when the blending ratio of the photosensitive agent is less than 0.01 parts by weight with respect to 100 parts by weight of the polyamic acid, the resulting photosensitive polyimide resin precursor composition is irradiated with ultraviolet rays, developed, and formed into a pattern. Can't get enough contrast.
[0047]
Furthermore, according to the photosensitive polyimide resin precursor composition according to the present invention, not only the blending ratio of the photosensitive agent to the polyamic acid is small, but also the exposure amount itself for exposing the resulting photosensitive polyimide resin precursor composition. It can reduce compared with the conventionally known photosensitive polyimide resin precursor composition. That is, in the conventional photosensitive polyimide resin precursor composition, an appropriate exposure amount is 300 to 1000 mJ / cm. ² In contrast, according to the photosensitive polyimide resin precursor composition according to the present invention, 5 to 20 mJ / cm. ² Sufficient resolution is possible with an exposure amount in the range.
[0048]
Thus, according to the present invention, as described above, by introducing fluorine atoms into the structure of the polyamic acid, the transparency of the polyamic acid is improved. As a result, the ratio of the photosensitizer to the polyamic acid is increased. Even if the exposure amount is reduced, it has sufficient sensitivity to light, and gives high contrast upon development after exposure.
[0049]
According to the present invention, the glycol (ether) is blended with polyamic acid together with the above photosensitizer as a dissolution regulator to obtain a photosensitive polyimide resin precursor composition. The glycol (ether) as such a dissolution regulator has a weight average molecular weight of usually 100 to 3000, preferably 200 to 2000, and most preferably 300 to 1000. According to the present invention, when the polyamic acid is heated and cured (imidized), the dissolution modifier is volatilized out of the resin together with the residual solvent, and is finally formed in the resin. It does not adversely affect the properties required for optical resins such as transparency of polyimide resin.
[0050]
According to the present invention, such a dissolution regulator is used in an amount of 5 to 50 parts by weight, preferably 10 to 40 parts by weight, based on 100 parts by weight of the polyamic acid. When the proportion of the dissolution regulator is less than 5 parts by weight relative to 100 parts by weight of the polyamic acid, after developing the resin film made of the resulting photosensitive polyimide resin precursor composition, when developing, The effect of suppressing the reduction of the thickness of the resin film (that is, the reduction in film thickness) is poor, the remaining film ratio after development is usually 50% or less, and the cross section of the obtained pattern is also a convex trapezoidal shape. is there. On the other hand, when it exceeds 50 parts by weight, the compatibility with the polyamic acid is deteriorated and the resolution may be lowered.
[0051]
According to the present invention, by using a dissolution modifier, the resin film made of the resulting photosensitive polyimide resin precursor composition is exposed to light and exposed to light. This causes a significant difference in the solubility of the part in the developer, and thus, during development, the unexposed part can be dissolved and removed without substantially dissolving the exposed part, thereby improving the residual film ratio of the resin film. According to a preferred embodiment, the shape of the pattern to be obtained can be controlled by selecting the blending amount of the dissolution regulator.
[0052]
That is, according to the present invention, the dissolution modifier is used in the range of 20 to 40 parts by weight, preferably 25 to 35 parts by weight, with respect to 100 parts by weight of the polyamic acid, whereby a remaining film ratio of 80% or more is obtained. The cross-sectional shape of the pattern can be a square. As a result, it is possible to form a pattern having a square cross-sectional shape (aspect ratio of 1) or a vertically long cross-sectional shape (aspect ratio of 1 or more), which has conventionally been difficult, by wet etching.
[0053]
According to the present invention, as described above, by using the dissolution regulator in an appropriate blending amount, the resin film made of the resulting photosensitive polyimide resin precursor composition is exposed to light and exposed, and then developed. A large difference is caused in the solubility of the exposed portion of the resin film and the unexposed portion in the developer, and thus the unexposed portion can be dissolved and removed without substantially dissolving the exposed portion during development. The shape of the pattern to be formed can be controlled.
[0054]
According to the present invention, a photosensitive polyimide resin precursor composition having high sensitivity can be obtained by blending a polyamic acid with a photosensitizer and a dissolution regulator as described above. According to such a photosensitive polyimide resin precursor composition, large area processing is possible. That is, since the pattern formation in the conventional optical element is performed by the dry process such as the reactive ion etching method as described above, the working time is long and the mass productivity is poor. The pattern formation using the polyimide resin precursor composition does not have these drawbacks, and the processing cost can be greatly reduced.
[0055]
Furthermore, according to the present invention, the surface of the pattern obtained by wet etching of the photosensitive polyimide resin precursor composition is very smooth, including the side surfaces. There is no light scattering due to the unevenness on the side surface of the pattern, which is a problem, and the transparency (light transmittance) is excellent.
[0056]
The optical polyimide resin according to the present invention can be obtained from such a photosensitive polyimide resin precursor composition. Specifically, for example, the photosensitive polyimide resin precursor composition is applied to the surface of a substrate such as a silicon substrate, a quartz substrate, a metal foil, a glass plate, or a polymer film, and is initially dried, so that the photosensitive polyimide resin precursor composition is applied. After forming the resin film made of the body composition, the resin film is irradiated with ultraviolet rays through a glass mask or the like so as to obtain a desired pattern. Next, in order to complete the photoreaction in this resin film, it is usually heated in the air after exposure at a temperature of 160 to 200 ° C., preferably 170 to 190 ° C. This is followed by development and further heating to imidize the desired pattern thus obtained. The heating temperature is usually in the range of 300 to 400 ° C., and the solvent removal and the curing reaction are performed in a vacuum or a nitrogen atmosphere. In this way, a pattern made of polyimide resin can be obtained. The film thickness of this polyimide resin can be controlled by the solid content concentration, viscosity, film forming conditions, etc. of the photosensitive polyimide resin precursor composition.
[0057]
The method for applying the photosensitive polyimide resin precursor composition to the surface of the substrate is not particularly limited, and for example, a general film forming method such as a spin coating method or a casting method can be used. Further, as the developer used for the development, an alkaline aqueous solution is usually used.
[0058]
Thus, an optical component such as an optical waveguide can be produced by forming a desired pattern on the substrate. For example, in the above-described optical waveguide, an overcladding layer made of another polyimide resin can be formed on the pattern obtained in this manner to form an embedded optical waveguide structure. Moreover, what is necessary is just to remove the said base material or an over clad layer by an etching etc., when obtaining a flexible optical waveguide.
[0059]
Thus, according to the present invention, a colorless and transparent optical waveguide having a large area is manufactured at a low cost by forming a polyimide resin having a pattern using the above-described photosensitive polyimide resin precursor composition. can do.
[0060]
Examples of the optical waveguide according to the present invention include a straight optical waveguide, a bent optical waveguide, a multilayer waveguide, a crossed optical waveguide, a Y-branch optical waveguide, a slab optical waveguide, a Mach-Zehnder optical waveguide, an AWG optical waveguide, a grating, and an optical waveguide. A lens etc. can be mentioned. Optical devices using these optical waveguides include wavelength filters, optical switches, optical splitters, optical multiplexers, optical multiplexers / demultiplexers, optical amplifiers, wavelength converters, wavelength dividers, optical splitters, directional couplers Furthermore, an optical transmission module in which laser diodes and photodiodes are hybrid-integrated can be used. The waveguide according to the present invention can also be formed on a conventional electric wiring board.
[0061]
Next, the manufacturing method of the optical waveguide using the photosensitive polyimide resin precursor composition by this invention is demonstrated.
[0062]
The manufacturing method of the optical waveguide according to the present invention is the same as the manufacturing method of a general optical waveguide except that pattern formation is directly performed using the photosensitivity of the photosensitive polyimide resin precursor composition. By this method, a planar optical waveguide, a ridge optical waveguide, a buried optical waveguide, etc. can be manufactured. The photosensitive polyimide resin precursor composition according to the present invention can be applied to any of the core layer forming material, the under cladding layer forming material, and the over cladding layer forming material, and at the same time. When used simultaneously for the core layer forming material and the cladding layer forming material, for example, by changing the tetracarboxylic dianhydride or diamine used, or changing the copolymer composition ratio thereof, for example, single mode When a waveguide is manufactured, a difference in refractive index of about 0.2 to 1.0% may be provided between the refractive indexes of both.
[0063]
In the optical waveguide, the core layer needs to have a higher refractive index than the cladding layer. In general, the relative refractive index difference Δ between them may be about 0.2 to 1.0% in the single mode. Here, the relative refractive index difference Δ is when n (core) is the refractive index of the core and n (cladding) is the refractive index of the cladding,
Δ = ((n (core) −n (cladding)) / n (core))) × 100 (%)
It is represented by
[0064]
As a method for adjusting the refractive index of the polyimide resin in this way, for example, a tetracarboxylic dianhydride having a fluorine atom in the molecule or a diamine having a fluorine atom in the molecule is used as a polyimide resin precursor. A method of producing a polyamic acid to obtain a polyimide resin having a lower refractive index than that, and using this to lower the refractive index of the polyimide resin can be mentioned. And a refractive index difference can be adjusted suitably by adjusting these content ratios.
[0065]
In the optical waveguide of the present invention, as described above, a polyimide resin obtained from the photosensitive polyimide resin precursor composition according to the present invention is used for the core layer, but the under cladding layer and the over cladding layer are formed from the core layer. As long as the material has a low refractive index, it is not limited to polyimide resin, and other resin materials can be used. However, from the viewpoint of heat resistance, it is preferable to use polyimide resin as a material not only in the core layer but also in the cladding layer.
[0066]
Hereinafter, a method for manufacturing an embedded optical waveguide as an example of an optical waveguide will be described with reference to the drawings. As shown in FIG. 3A, a photosensitive polyimide resin precursor composition that gives a polyimide resin having a higher refractive index than that of the substrate is applied onto the substrate 1 and dried to form a photosensitive polyimide resin precursor. A resin film 2 is formed. Next, as shown in FIG. 3B, a glass mask 3 is placed on the resin film 2 so as to obtain a desired pattern, and ultraviolet rays are irradiated from above. Then, after performing post-exposure heating, development is performed using a developer, and after processing into a predetermined pattern, heating and curing (imidization) are performed, as shown in FIG. A pattern made of polyimide resin is formed as the core layer 4. Next, as shown in FIG. 3D, an embedded optical waveguide is obtained by forming an over clad layer 5 made of a material having a refractive index lower than that of the core pattern layer 4 on the core pattern layer 4. be able to.
[0067]
As a specific example of such an embedded optical waveguide structure, for example, as shown in FIGS. 4A to 4C, a core layer 4 having a Y-shaped pattern is provided on a substrate 1, and this core layer is A Y-branch type optical waveguide that is included in the over clad layer 5 can be exemplified.
[0068]
Further, another method for manufacturing an optical waveguide will be described with reference to the drawings. As shown in FIG. 5A, first, a substrate 6 made of a material that can be etched in the final process and can be peeled off from an under cladding layer described later is prepared. Next, as shown in FIG. 5B, an under cladding layer 7 is formed on the substrate 6. Further, as shown in FIG. 5C, a resin film 8 made of the photosensitive polyimide resin precursor composition of the present invention which gives a polyimide resin having a refractive index higher than that of the under clad layer on the under clad layer 7. Form. Next, in the same manner as the above-described method for manufacturing an embedded optical waveguide, a glass mask is placed on the resin film 8 so as to obtain a desired pattern, irradiated with ultraviolet rays from above, and heated after exposure. Thereafter, development is performed using a developing solution, and after processing into a predetermined pattern, the core layer 9 is formed as a pattern made of polyimide resin by heating and curing (imidization), as shown in FIG. Form. Next, as shown in FIG. 5E, an over clad layer 10 made of a material having a refractive index lower than that of the core layer is formed on the core layer 9. Thereafter, by removing the substrate 6 by etching, a flexible optical waveguide from which the rigid substrate is removed can be obtained as shown in FIG.
[0069]
In the manufacture of such a flexible optical waveguide, the material of the substrate 6 is not particularly limited as long as it has conditions that enable the etching removal, and examples thereof include metals, inorganic materials, and organic films. Used.
[0070]
The material for forming the under cladding layer 7 and the material for forming the over cladding layer 10 may be the same or different. Further, as a material for forming these cladding layers, a material obtained by removing the photosensitive agent from the photosensitive polyimide precursor precursor of the present invention may be used.
[0071]
【Example】
EXAMPLES The present invention will be described below with reference to examples together with comparative examples, but the present invention is not limited to these examples.
[0072]
Example 1
In a 500 mL separable flask under nitrogen atmosphere, 16.7 g (0.05 mol) of 2,2-bis (4-aminophenyl) hexafluoropropane (BAAF) was added to N, N-dimethylacetamide (DMAc) 155. Dissolved in 6 g. While stirring, 22.2 g (0.05 mol) of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) was added to this solution and then stirred at room temperature for 24 hours. Thus, a polyamic acid solution was prepared.
[0073]
Next, 0.019 g (0.05 parts by weight with respect to 100 parts by weight of the polyamic acid (solid content) of the polyamic acid solution) and polyethylene glycol dimethyl ether 5 having a weight average molecular weight of 500 are added to the polyamic acid solution. .8 g (15 parts by weight with respect to 100 parts by weight of polyamic acid in the polyamic acid solution) was added to obtain a photosensitive polyimide resin precursor composition as a solution.
[0074]
The photosensitive polyimide resin precursor composition is applied on a synthetic quartz glass substrate having a thickness of 1.0 mm by spin coating and dried at 90 ° C. for about 15 minutes. A resin film made of a material was formed. A glass mask on which a 70 mm long pattern having a line width of 7 μm is drawn at a pitch of 50 μm is placed on this resin film, and 10 mJ / cm from above. ² After being irradiated with UV light, it was heated at 170 ° C. for 10 minutes (post-exposure heating). Next, using a 1.5% by weight aqueous solution of tetramethylammonium hydroxide as a developing solution, development was performed at 35 ° C. and rinsing with water to form a core layer having a predetermined pattern. Thereafter, the mixture was heated at 380 ° C. for 2 hours in a vacuum atmosphere to remove the solvent from the core layer and complete the imidization (curing) of the polyamic acid. It was 6.8 micrometers when the thickness of the core layer which consists of a pattern of the polyimide resin obtained in this way was measured with the contact-type surface roughness meter.
[0075]
In order to form an overcladding layer on this core layer, trifluoromethylpyromellitic dianhydride and 2,2′-bis (trifluoromethyl) -4,4′-diaminodiphenyl were separately added in a solvent, A polyamic acid solution was prepared by reacting at an equimolar ratio to give a polyimide resin having a smaller refractive index than the polyimide resin of the core layer.
[0076]
The polyamic acid solution is applied onto the core layer by spin coating, and then heated at 380 ° C. for 2 hours in a vacuum atmosphere to form an overcladding layer, thus obtaining a buried optical waveguide. It was. After the end face treatment of this optical waveguide, the light propagation loss was measured by the cutback method through light having a wavelength of 1300 nm, and it was 1.3 dB / cm.
[0077]
Example 2
In Example 1, an embedded optical waveguide was obtained in the same manner as in Example 1 except that 2 parts by weight of a photosensitive agent (EDHP) was used with respect to 100 parts by weight of polyamic acid (solid content). With respect to this optical waveguide, the optical propagation loss was measured in the same manner as in Example 1. As a result, it was 1.4 dB / cm.
[0078]
Example 3
In Example 1, an embedded optical waveguide was obtained in the same manner as in Example 1 except that 4 parts by weight of a photosensitizer (EDHP) was used with respect to 100 parts by weight of polyamic acid (solid content). With respect to this optical waveguide, the optical propagation loss was measured in the same manner as in Example 1. As a result, it was 1.6 dB / cm.
[0079]
Example 4
In Example 1, a photosensitive polyimide was prepared in the same manner as in Example 1 except that 4 parts by weight of a photosensitizer (EDHP) and 10 parts by weight of polyethylene glycol dimethyl ether were used with respect to 100 parts by weight of polyamic acid (solid content). A resin precursor composition was obtained as a solution.
[0080]
A solution of the photosensitive polyimide resin precursor composition is applied onto a silicon wafer with a thermal oxide film by a spin coating method, and heated and dried at 90 ° C. for about 15 minutes. A resin film having a thickness of 8 μm made of the composition was formed. Thereafter, in the same manner as in Example 1, the resin film was irradiated with ultraviolet rays through a glass mask, subjected to post-exposure heating, and developed to obtain a core layer having a predetermined pattern and a thickness of 6 μm. . Therefore, the remaining film rate was 75%. Here, the remaining film ratio is ((thickness of resin film before light irradiation (μm) −thickness of resin film after development (μm)) / thickness of resin film before irradiation (μm)) × 100 (%) Defined by
[0081]
Example 5
In Example 1, a photosensitive polyimide was prepared in the same manner as in Example 1 except that 4 parts by weight of a photosensitizer (EDHP) and 15 parts by weight of polyethylene glycol dimethyl ether were used with respect to 100 parts by weight of polyamic acid (solid content). A resin precursor composition was obtained as a solution. Using this, a resin film having a thickness of 8 μm was formed in the same manner as in Example 4, and the resin film was irradiated with ultraviolet rays, heated after exposure, developed, and developed to have a thickness 7 of a predetermined pattern. A core layer of .5 μm was obtained. Therefore, the remaining film rate was 94%.
[0082]
Example 6
In Example 1, a photosensitive polyimide was prepared in the same manner as in Example 1 except that 4 parts by weight of a photosensitive agent (EDHP) and 20 parts by weight of polyethylene glycol dimethyl ether were used with respect to 100 parts by weight of polyamic acid (solid content). A resin precursor composition was obtained as a solution. Using this, a resin film having a thickness of 8 μm was formed in the same manner as in Example 4, and the resin film was irradiated with ultraviolet rays, heated after exposure, developed, and developed to have a thickness of 6 of a predetermined pattern. A core layer of .5 μm was obtained. Therefore, the remaining film rate was 81%.
[0083]
Comparative Example 1
In Example 1, a photosensitive polyimide resin precursor composition was prepared in the same manner as in Example 1 except that only 4 parts by weight of the photosensitive agent (EDHP) was used with respect to 100 parts by weight of the polyamic acid (solid content). Obtained as a solution. Using this, a resin film having a thickness of 8 μm was formed in the same manner as in Example 4. The resin film was irradiated with ultraviolet rays, heated after exposure, developed, and developed to have a thickness of 1 of a predetermined pattern. A core layer of .5 μm was obtained. Therefore, the remaining film rate was 19%.
[0084]
Comparative Example 2
In Example 1, photosensitive polyimide was used in the same manner as in Example 1 except that 4 parts by weight of photosensitizer (EDHP) and 60 parts by weight of polyethylene glycol dimethyl ether were used with respect to 100 parts by weight of polyamic acid (solid content). A resin precursor composition was obtained as a solution. Using this, a resin film having a thickness of 8 μm was formed in the same manner as in Example 4.
[0085]
The resin film was irradiated with ultraviolet rays in the same manner as in Example 4, heated after exposure, and then observed, and it was confirmed that phase separation occurred. Although development of this resin film was performed, contrast could not be obtained between the exposed part and the unexposed part, and a required pattern could not be obtained.
[0086]
Example 7
Under a nitrogen atmosphere, 8.81 g (0.04 mol) of 2,2′-difluorobenzidine (FBZ) was dissolved in 79.7 g of N, N-dimethylacetamide (DMAc) in a separable flask having a capacity of 300 mL. While stirring, 17.8 g (0.04 mol) of 2,2-bis (3,4-dicarboxyphenyl) hexafluorobropan dianhydride (6FDA) was added to the solution, and then at room temperature for 24 hours. Stirring to obtain a polyamic acid solution.
[0087]
A photosensitive polyimide resin precursor composition is prepared by adding 2 parts by weight of a photosensitizer (EDHP) and 15 parts by weight of polyethylene glycol dimethyl ether having a weight average molecular weight of 500 to 100 parts by weight of polyamic acid (solid content) of the polyamic acid solution. The product was obtained as a solution.
[0088]
A solution of the photosensitive polyimide resin precursor composition is applied on a synthetic quartz glass substrate having a thickness of 1.0 mm by a spin coating method, heated at 90 ° C. for about 15 minutes, and dried, and then the photosensitive polyimide resin. A resin film made of the precursor composition was formed. A glass mask on which a 70 mm long pattern having a line width of 6 μm is drawn at a pitch of 100 μm is placed on this resin film, and 10 mJ / cm is applied to the entire surface from above. ² Were then irradiated at 170 ° C. for 10 minutes. The thickness of the resin film after exposure thus obtained was 8.0 μm.
[0089]
Next, an ethanol / alkaline aqueous solution containing tetramethylammonium hydroxide was used as a developing solution, developed at 35 ° C., and then rinsed with water to form a core layer having a required pattern. Thus, the thickness of the resin film obtained by development was 7.0 μm.
[0090]
Thereafter, the mixture was heated at 380 ° C. for 2 hours in a vacuum atmosphere to remove the solvent from the core layer and complete imidization of the polyamic acid. Thus, when the thickness of the core layer which consists of a pattern of a polyimide resin was measured with the contact-type surface roughness meter, it was 6.3 micrometers.
[0091]
In order to form an overcladding layer on this core layer, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2-bis (4-amino) were separately used. Phenyl) hexafluoropropane (BAAF) was reacted in an equimolar ratio in a solvent to prepare a polyamic acid solution that gave a polyimide resin having a smaller refractive index than the polyimide resin of the core layer.
[0092]
The polyamic acid solution is applied onto the core layer by spin coating, and then heated at 380 ° C. for 2 hours in a vacuum atmosphere to form an overcladding layer, thus obtaining an embedded optical waveguide. It was. After the end face treatment of this optical waveguide, the light propagation loss was measured by the cutback method through light having a wavelength of 1300 nm, and it was 0.7 dB / cm.
[0093]
Example 8
In Example 7, an embedded optical waveguide was obtained in the same manner as in Example 7 except that 4 parts by weight of the photosensitizer (EDHP) was used with respect to 100 parts by weight of the polyamic acid (solid content). With respect to this optical waveguide, the optical propagation loss was measured in the same manner as in Example 7. As a result, it was 1.1 dB / cm.
[0094]
Example 9
In Example 7, an embedded optical waveguide was obtained in the same manner as in Example 7 except that 0.5 parts by weight of the photosensitive agent (EDHP) was used with respect to 100 parts by weight of the polyamic acid (solid content). . With respect to this optical waveguide, when the optical propagation loss was measured in the same manner as in Example 7, it was 0.6 dB / cm.
[0095]
Example 10
In Example 7, with the exception of using 20 parts by weight of polyethylene glycol having a weight average molecular weight of 200 instead of polyethylene glycol dimethyl ether as a dissolution regulator for 100 parts by weight of polyamic acid (solid content), Similarly, the photosensitive polyimide resin precursor composition was obtained as a solution. An embedded optical waveguide was obtained in the same manner as in Example 7 except that this photosensitive polyimide resin precursor composition solution was used. With respect to this optical waveguide, the optical propagation loss was measured in the same manner as in Example 7. As a result, it was 0.7 dB / cm.
[0096]
Comparative Example 3
In Example 7, the photosensitive polyimide resin precursor composition was dissolved in the same manner as in Example 7 except that 6 parts by weight of the photosensitive agent (EDHP) was used with respect to 100 parts by weight of the polyamic acid (solid content). Got as. In the same manner as in Example 7, a buried optical waveguide was produced using the solution of the photosensitive polyimide resin precursor composition. With respect to this optical waveguide, the optical propagation loss was measured in the same manner as in Example 7. As a result, it was 3.0 dB / cm.
[0097]
Comparative Example 4
In Example 7, a photosensitive polyimide resin precursor composition was obtained as a solution in the same manner as in Example 7 except that the dissolution regulator was not used. Using this solution of the photosensitive polyimide resin precursor composition, an attempt was made to form a pattern made of polyimide resin in the same manner as in Example 7, but the contrast was insufficient in the development step, and the resulting core The layer thickness was 2 μm.
[0098]
Using the core layer thus obtained, an optical waveguide was manufactured in the same manner as in Example 7. With respect to this optical waveguide, an attempt was made to measure the light propagation loss by the cut-back method in the same manner as in Example 7, but no light was guided.
[0099]
Example 11
Under a nitrogen atmosphere, 16.0 g (0.05 mol) of 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (TFMB) was added to N, N-dimethylacetamide (0.05 mol) in a 500 mL separable flask. DMAc) was dissolved in 152.8 g. While stirring, 22.2 g (0.05 mol) of 2,2-bis (3,4-dicarboxyphenyl) hexafluorobropan dianhydride (6FDA) was added to this solution, and then at room temperature for 24 hours. Stirring to prepare a polyamic acid solution.
[0100]
Next, with respect to 100 parts by weight of the polyamic acid (solid content) of this polyamic acid solution, 1.0 part by weight (0.38 g) of a photosensitizer (EDHP) and 15 parts by weight of polyethylene glycol dimethyl ether having a weight average molecular weight of 500 (5 .73 g) was added to obtain a photosensitive polyimide resin precursor composition as a solution.
[0101]
The above polyamic acid solution is applied onto a synthetic quartz glass substrate having a thickness of 1.0 mm by a spin coating method, dried at 90 ° C. for about 15 minutes, and then heated at 380 ° C. for 2 hours in a vacuum atmosphere. Was cured (imidized). The film thickness of the polyimide thus obtained was 10 μm. This polyimide film was used as the under cladding layer of the optical waveguide.
[0102]
Next, the photosensitive polyimide resin precursor composition A is applied onto the undercladding layer by spin coating, and dried at 90 ° C. for about 15 minutes to form a resin film comprising the photosensitive polyimide resin precursor composition. Formed. A glass mask on which a pattern of 70 mm in length having a line width of 8 μm was drawn at a pitch of 50 μm was placed on this resin film, and 10 mJ / cm from above. ² After being irradiated with UV rays, it was heated at 180 ° C. for 10 minutes (heated after exposure). Next, a 5% by weight aqueous solution of tetramethylammonium hydroxide was used as a developing solution, developed at 35 ° C., and rinsed with water to form a core layer of an optical waveguide having a predetermined pattern. Thereafter, heating was performed at 360 ° C. for 2 hours in a vacuum atmosphere to remove the solvent from the core layer and complete imidization (curing) of the polyamic acid. It was 6.5 micrometers when the thickness of the core layer which consists of a pattern of the polyimide resin obtained in this way was measured with the contact-type surface roughness meter.
[0103]
After coating the above polyamic acid solution on this core layer by spin coating, it is heated in a vacuum atmosphere at 380 ° C. for 2 hours to form a 20 μm-thick overcladding layer. A waveguide was obtained. After the end face treatment of this optical waveguide was performed using a dicing apparatus, the light propagation loss was measured by the cut-back method through light having a wavelength of 1550 nm, which was 0.8 dB / cm.
[0104]
Example 12
Under a nitrogen atmosphere, 11.0 g (0.05 mol) of 2,2′-difluorobenzidine (FBZ) was dissolved in 132.8 g of N, N-dimethylacetamide (DMAc) in a 500 mL separable flask. While stirring, 22.2 g (0.05 mol) of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) was added to this solution and then stirred at room temperature for 24 hours. Thus, a polyamic acid solution was prepared.
[0105]
Next, 1.0 part by weight of a photosensitizing agent (EDHP) and 15 parts by weight of polyethylene glycol dimethyl ether having a weight average molecular weight of 500 are added to 100 parts by weight of the polyamic acid (solid content) to the polyamic acid solution to obtain a photosensitive polyimide. A resin precursor composition was obtained as a solution.
[0106]
An embedded optical waveguide was obtained in the same manner as in Example 11 except that this photosensitive polyimide resin precursor composition was used for forming the core layer. With respect to this optical waveguide, the optical propagation loss was measured in the same manner as in Example 11. As a result, it was 0.9 dB / cm.
[0107]
Example 13
Under a nitrogen atmosphere, in a 500 mL separable flask, 8.0 g (0.025 mol) of 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (TFMB) and 4,4′-oxydi 5.0 g (0.025 mol) of aniline (ODA) was dissolved in 14.08 g of N, N-dimethylacetamide (DMAc). With stirring, 22.2 g (0.05 mol) of 2,2-pis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) was added to this solution, and then stirred at room temperature for 24 hours. Thus, a polyamic acid solution was prepared.
[0108]
Next, 1.0 part by weight of a photosensitizing agent (EDHP) and 15 parts by weight of polyethylene glycol dimethyl ether having a weight average molecular weight of 500 are added to 100 parts by weight of the polyamic acid (solid content) to the polyamic acid solution to obtain a photosensitive polyimide. A resin precursor composition was obtained as a solution.
[0109]
An embedded optical waveguide was obtained in the same manner as in Example 11 except that the photosensitive polyimide resin precursor composition was used to form the core layer. With respect to this optical waveguide, when the optical propagation loss was measured in the same manner as in Example 1, it was 0.9 dB / cm.
[0110]
Example 14
Under a nitrogen atmosphere, 16.0 g (0.05 mol) of 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (TFMB) was added to N, N-dimethylacetamide (0.05 mol) in a 500 mL separable flask. DMAc) was dissolved in 130.2 g. While stirring, 11.2 g (0.025 mol) of 2,2-bis (3.4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and pyromellitic dianhydride (PMDA) were added to this solution. 5.45 g (0.025 mol) was added simultaneously, followed by stirring at room temperature for 24 hours to prepare a polyamic acid solution.
[0111]
Next, 1.0 part by weight of a photosensitizing agent (EDHP) and 15 parts by weight of polyethylene glycol dimethyl ether having a weight average molecular weight of 500 are added to 100 parts by weight of the polyamic acid (solid content) to the polyamic acid solution to obtain a photosensitive polyimide. A resin precursor composition was obtained as a solution.
[0112]
An embedded optical waveguide was obtained in the same manner as in Example 11 except that the photosensitive polyimide resin precursor composition was used to form the core layer. With respect to this optical waveguide, the optical propagation loss was measured in the same manner as in Example 11. As a result, it was 0.8 dB / cm.
[0113]
Example 15
In a 500 mL separable flask under nitrogen atmosphere, 16.0 g (0.05 mol) of N, N-dimethylacetamide (DMAc) 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (TFMB) ) 13.94 g. While stirring, 11.2 g (0.025 mol) of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and bis (3,4-dicarboxyphenyl) were added to this solution. ) Etheric acid dianhydride (OPDA) (7.76 g, 0.025 mol) was added at the same time, and the mixture was stirred at room temperature for 24 hours to prepare a polyamic acid solution.
[0114]
Next, 1.0 part by weight of a photosensitizing agent (EDHP) and 15 parts by weight of polyethylene glycol dimethyl ether having a weight average molecular weight of 500 are added to 100 parts by weight of the polyamic acid (solid content) to the polyamic acid solution to obtain a photosensitive polyimide. A resin precursor composition was obtained as a solution.
[0115]
An embedded optical waveguide was obtained in the same manner as in Example 11 except that the photosensitive polyimide resin precursor composition was used to form the core layer. With respect to this optical waveguide, the optical propagation loss was measured in the same manner as in Example 11. As a result, it was 1.1 dB / cm.
[0116]
Example 16
In a 500 mL separable flask under nitrogen atmosphere, 16.0 g (0.05 mol) of N, N-dimethylacetamide (DMAc) 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (TFMB) ) It was dissolved in 137.8 g. While stirring, 11.2 g (0.025 mol) of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropan dianhydride (6FDA) and 3,3′4,4′- were added to this solution. 7.4 g (0.025 mol) of biphenyltetracarboxylic dianhydride (BPDA) was added simultaneously, followed by stirring at room temperature for 24 hours to prepare a polyamic acid solution.
[0117]
Next, 1.0 part by weight of a photosensitizing agent (EDHP) and 15 parts by weight of polyethylene glycol dimethyl ether having a weight average molecular weight of 500 are added to 100 parts by weight of the polyamic acid (solid content) to the polyamic acid solution to obtain a photosensitive polyimide. A resin precursor composition was obtained as a solution.
[0118]
An embedded optical waveguide was obtained in the same manner as in Example 11 except that the photosensitive polyimide resin precursor composition was used for forming the core layer. With respect to this optical waveguide, the optical propagation loss was measured in the same manner as in Example 11. As a result, it was 1.1 dB / cm.
[0119]
Example 17
In a 500 mL separable flask under nitrogen atmosphere, 8.0 g (0.025 mol) of 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (TFMB) and 2,2-bis (4 -Aminophenyl) hexafluoropropane (BIS-A-AF) 8.4 g (0.025 mol) was dissolved in N, N-dimethylacetamide) DMAc) 154.3 g. While stirring, 22.2 g (0.05 mol) of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) was added to this solution and then stirred at room temperature for 24 hours. Thus, a polyamic acid solution was prepared.
[0120]
Example 11 except that the polyamic acid varnish was used to form the undercladding layer and the overcladding layer, and that the photosensitive polyimide resin precursor composition A prepared in Example 11 was used to form the core layer. In the same manner, an embedded optical waveguide was obtained. With respect to this optical waveguide, the optical propagation loss was measured in the same manner as in Example 11. As a result, it was 0.9 dB / cm.
[0121]
Example 18
In Example 11, an embedded optical waveguide was obtained in the same manner as in Example 11 except that 3 parts by weight of a photosensitive agent (EDHP) was used with respect to 100 parts by weight of polyamic acid (solid content). With respect to this optical waveguide, the optical propagation loss was measured in the same manner as in Example 11. As a result, it was 1.1 dB / cm.
[0122]
Example 19
In Example 11, an embedded optical waveguide was obtained in the same manner as in Example 11 except that 0.05 part by weight of the photosensitive agent (EDHP) was used with respect to 100 parts by weight of the polyamic acid (solid content). . With respect to this optical waveguide, the optical propagation loss was measured in the same manner as in Example 11. As a result, it was 0.8 dB / cm.
[0123]
Example 20
In Example 11, a buried optical waveguide was obtained in the same manner as in Example 11 except that polypropylene glycol dimethyl ether having a weight average molecular weight of 500 was used instead of polyethylene glycol dimethyl ether. With respect to this optical waveguide, the optical propagation loss was measured in the same manner as in Example 11. As a result, it was 0.8 dB / cm.
[0124]
Example 21
In Example 11, Example 11 was used except that 1.0 part by weight of a photosensitizer (EDHP) and 30 parts by weight of polyethylene glycol dimethyl ether having a weight average molecular weight of 500 were used with respect to 100 parts by weight of polyamic acid (solid content). In the same manner as above, a photosensitive polyimide resin precursor composition was obtained as a solution.
[0125]
The polyamic acid solution prepared in Example 11 was applied on a synthetic quartz glass substrate having a thickness of 1.0 mm by spin coating, dried at 90 ° C. for about 15 minutes, and then in a vacuum atmosphere at 360 ° C. for 2 hours. It was heated and cured (imidized). The film thickness of the polyimide thus obtained was 10 μm. This was used as the under cladding layer of the optical waveguide.
[0126]
Next, the photosensitive polyimide resin precursor composition is applied onto the undercladding layer by a spin coating method, and dried at 90 ° C. for about 15 minutes, so that the photosensitive polyimide resin precursor fine composition is formed. A resin film was formed. A glass mask on which a pattern with a length of 70 mm having a line width of 8 μm was drawn at a pitch of 50 μm was placed on this resin film, and 10 nJ / cm from above. ² After being irradiated with UV rays, it was heated at 180 ° C. for 10 minutes (heated after exposure). Next, a 5% by weight aqueous solution of tetramethylammonium hydroxide was used as a developing solution, developed at 35 ° C., and rinsed with water to form a core layer of an optical waveguide having a predetermined pattern. The remaining film ratio of the core layer was 80%. Further, when the cross-sectional shape of the core layer was examined, it was a square having a base angle of 88 to 90 °. Thereafter, the mixture was heated at 360 ° C. for 2 hours in a vacuum atmosphere to remove the solvent from the core layer and complete the curing (imidation) of the polyamic acid.
[0127]
The same polyamic acid solution used for forming the undercladding layer was applied on the core layer by spin coating, and then heated at 360 ° C. for 2 hours in a vacuum atmosphere to form a 20 μm thick overclad. Layers were formed, thus obtaining a buried optical waveguide. After the end face treatment of this optical waveguide was performed using a dicing apparatus, the light propagation loss was measured by the cut-back method through light having a wavelength of 1550 nm, which was 0.5 dB / cm.
[0128]
Example 22
In Example 11, a polyamic acid solution and a photosensitive polyimide resin precursor were used in the same manner as in Example 11 except that 30 parts by weight of polypropylene glycol having a weight average molecular weight of 300 was used instead of polyethylene glycol dimethyl ether as a dissolution regulator. Each body composition was prepared, and using them, an optical waveguide was produced in the same manner as in Example 11, and the residual film ratio, the bottom angle of the core layer, and the propagation loss of the obtained optical waveguide were measured. They were 85%, 88-90 ° and 0.5 dB / cm, respectively.
[0129]
Example 23
In Example 11, a polyamic acid solution and a photosensitive polyimide resin were used in the same manner as in Example 11 except that 30 parts by weight of polypropylene glycol diphenyl ether having a weight average molecular weight of 400 was used in place of polyethylene glycol dimethyl ether as a dissolution regulator. Precursor compositions were prepared, and using these, optical waveguides were produced in the same manner as in Example 11, and the development residual film ratio, the bottom angle of the core layer, and the propagation loss of the obtained optical waveguides were measured. However, they were 80%, 88 to 90 °, and 0.5 dB / cm, respectively.
[0130]
Comparative Example 5
In Example 11, an embedded optical waveguide was obtained in the same manner as in Example 11 except that 7 parts by weight of a photosensitive agent (EDHP) was used with respect to 100 parts by weight of polyamic acid (solid content). With respect to this optical waveguide, the light propagation loss was measured in the same manner as in Example 11. As a result, it was 2.4 dB / cm.
[0131]
Comparative Example 6
In Example 11, an embedded optical waveguide is obtained in the same manner as in Example 11 except that 0.005 part by weight of the photosensitive agent (EDHP) is used with respect to 100 parts by weight of the polyamic acid (solid content). However, it was not possible to obtain contrast between the exposed portion and the unexposed portion during development, and the core pattern of the optical waveguide could not be formed.
[0132]
Comparative Example 7
In Example 11, an attempt was made to obtain an embedded optical waveguide in the same manner as in Example 11 except that 60 parts by weight of polyethylene glycol dimethyl ether was used with respect to 100 parts by weight of polyamic acid (solid content). In the post-exposure heating stage, phase separation occurred in the polyamic acid film, and a pattern with the desired resolution could not be obtained, and the core pattern of the optical waveguide could not be formed.
[0133]
Comparative Example 8
In Example 11, a buried optical waveguide was obtained in the same manner as in Example 11 except that 3 parts by weight of polyethylene glycol dimethyl ether having a weight average molecular weight of 500 was used per 100 parts by weight of polyamic acid (solid content). However, it was impossible to obtain contrast between the exposed area and the unexposed area during development, and the core pattern of the optical waveguide could not be formed.
[0134]
Comparative Example 9
The same polyamic acid solution as in Example 11 was applied on a synthetic quartz glass substrate having a thickness of 1.0 mm by spin coating, dried at 90 ° C. for about 15 minutes, and then heated at 360 ° C. for 2 hours in a vacuum atmosphere. The polyamic acid was cured (imidized). The film thickness of the polyimide thus obtained was 10 μm. This polyimide film was used as an under cladding layer.
[0135]
Next, the same photosensitive polyimide resin precursor composition as in Example 11 was applied onto this undercladding layer by a spin coating method, and dried at 90 ° C. for about 15 minutes. The photosensitive polyimide resin precursor composition was then applied. The resin film which consists of was formed. Furthermore, it was heated at 360 ° C. for 2 hours in a vacuum atmosphere to remove the solvent from the core layer and complete the curing (imidization) of the polyamic acid.
[0136]
Next, the core layer is formed by a conventionally known reactive ion etching method using oxygen plasma so as to obtain a predetermined pattern in which a 70 mm long pattern having a line width of 8 μm is drawn at a pitch of 50 μm. Was processed. After applying the same polyamic acid solution used for forming the undercladding layer under the core layer thus obtained by spin coating, it was heated in a vacuum atmosphere at 360 ° C. for 2 hours, An over clad layer having a thickness of 20 μm was formed, and thus an embedded optical waveguide was obtained. After the end face treatment of this optical waveguide was performed using a dicing apparatus, the light propagation loss was measured by the cut-back method through light having a wavelength of 1550 nm, which was 1.2 dB / cm.
[0137]
【The invention's effect】
As described above, since the photosensitive polyimide resin precursor composition of the present invention is a composition in which a dissolution modifier is blended while the blending amount of the photosensitive agent is small compared to the conventional one, a small amount is added to the film. After exposure by UV irradiation, heating and development after exposure can yield a polyimide resin having a required pattern with high contrast.
[0138]
In particular, by using a polyamic acid that is a precursor of a polyimide resin, which is obtained from a tetracarboxylic dianhydride having a fluorine atom and a diamine, respectively, there is substantially no coloring, it is transparent, and it has heat resistance. In addition, a polyimide resin that can be suitably used as an optical resin can be obtained. Therefore, for example, by using such a polyimide resin as a core layer, an optical waveguide with little optical loss can be obtained.
[Brief description of the drawings]
FIG. 1 shows a typical cross-sectional shape of a pattern obtained by a wet process of a polyimide resin film.
FIG. 2 shows a square cross-sectional shape of a pattern obtained by a wet process of a polyimide resin film according to the present invention.
FIGS. 3A to 3D are views showing a manufacturing process of a buried optical waveguide according to the present invention. FIGS.
4A is a perspective view showing a branched optical waveguide, FIG. 4B is a cross-sectional view taken along the line BB, and FIG. 4C is a cross-sectional view taken along the line CC.
FIGS. 5A to 5F are views showing manufacturing steps of another form of optical waveguide according to the present invention. FIGS.
[Explanation of symbols]
1 ... Board
2 ... Resin film comprising photosensitive polyimide resin precursor composition
3 ... Glass mask
4. Core layer (core pattern layer)
5 ... Over clad layer
6 ... Board
7 ... Under clad layer
8 ... Resin film comprising photosensitive polyimide resin precursor composition
9 ... Core layer
10 ... Over clad layer

Claims (9)

(A) polyamic acid obtained from tetracarboxylic dianhydride and diamine;
(B) General formula (I) with respect to 100 parts by weight of this polyamic acid

(In the formula, Ar represents an aromatic group having a nitro group in the ortho position relative to the bonding position to the 1,4-dihydropyridine ring, R ₁ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ₂ , R ₃ , R ₄ and R ₅ each independently represent a hydrogen atom or an alkyl group having 1 or 2 carbon atoms.)
0.01 part by weight or more and less than 5 parts by weight of a 1,4-dihydropyridine derivative represented by:
(C) at least selected from polyethylene glycol, polyethylene glycol monomethyl ether, polyethylene glycol dimethyl ether, polyethylene glycol monophenyl ether, polyethylene glycol diphenyl ether, polypropylene glycol, polypropylene glycol monomethyl ether, polypropylene glycol dimethyl ether, polypropylene glycol monophenyl ether and polypropylene glycol diphenyl ether 1 type of glycol (ether) 5-50 weight part is contained, The photosensitive polyimide resin precursor composition characterized by the above-mentioned. 2. The photosensitive polyimide resin precursor composition according to claim 1, wherein the 1,4-dihydropyridine derivative is 1-ethyl-3,5-dimethoxycarbonyl-4- (2-nitrophenyl) -1,4-dihydropyridine. The photosensitive polyimide resin precursor composition according to claim 1, wherein the glycol (ether) has a weight average molecular weight in the range of 100 to 3,000. The photosensitive polyimide resin precursor composition according to claim 1, wherein the tetracarboxylic dianhydride has a fluorine atom in the molecule. The photosensitive polyimide resin precursor composition according to claim 1, wherein the diamine has a fluorine atom in the molecule. Polyamic acid is represented by the general formula (II)

(Wherein R ₆ represents the following formulas (IIa), (IIb), (IIc), (IId) and (IIe)

At least one tetravalent group selected from the tetravalent groups represented by the formula: wherein R ₇ is represented by the following formulas (IIf), (IIg), (IIh) and (IIi):

And at least one divalent group selected from divalent groups represented by: )
The photosensitive polyimide resin precursor composition of Claim 1 which has a repeating unit represented by these. An optical polyimide resin obtained by irradiating the photosensitive polyimide resin precursor composition according to any one of claims 1 to 6 with ultraviolet rays, followed by heating after exposure, development, and heating. An optical waveguide comprising a core layer made of the optical polyimide resin according to claim 7 as a cladding layer. In the manufacturing method of the optical waveguide according to claim 8,
(A) polyamic acid obtained from tetracarboxylic dianhydride and diamine;
(B) General formula (I) with respect to 100 parts by weight of this polyamic acid

(In the formula, Ar represents an aromatic group having a nitro group in the ortho position relative to the bonding position to the 1,4-dihydropyridine ring, R ₁ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ₂ , R ₃ , R ₄ and R ₅ each independently represent a hydrogen atom or an alkyl group having 1 or 2 carbon atoms.)
0.01 part by weight or more and less than 5 parts by weight of a 1,4-dihydropyridine derivative represented by:
(C) at least selected from polyethylene glycol, polyethylene glycol monomethyl ether, polyethylene glycol dimethyl ether, polyethylene glycol monophenyl ether, polyethylene glycol diphenyl ether, polypropylene glycol, polypropylene glycol monomethyl ether, polypropylene glycol dimethyl ether, polypropylene glycol monophenyl ether and polypropylene glycol diphenyl ether A photosensitive polyimide resin precursor composition containing 20 to 40 parts by weight of one kind of glycol (ether) having a weight average molecular weight of 200 to 2000 is applied on a substrate to form a photosensitive resin film, and through a mask. After irradiating with ultraviolet rays, it is heated after exposure, developed, heated, and a core layer having a square cross section Method of manufacturing an optical waveguide, which comprises forming.

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